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| United States Patent |
6,127,109
|
|
Goan
|
October 3, 2000
|
Silver halide light sensitive photographic material
Abstract
A silver halide light sensitive photographic material is disclosed,
comprising a support having thereon hydrophilic colloid layers including a
silver halide emulsion layer, wherein (i) at least 50% of the total
projected area of silver halide grains contained in the emulsion layer is
accounted for by tabular grains having an aspect ratio of 3 to 15, (ii)
the tabular grains each comprising an inner region which accounts for 70%
by volume of the grain and a residual outer region, the outer region
containing at least 75% of total iodide contained in the grain, and (iii)
the tabular grains each having an outermost layer, a halide content
distribution among the tabular grains with respect to the outermost layer
being not more than 20%; and wherein at least one of the hydrophilic
colloid layers contains a sulfur containing compound, which has a
water-solubilizing group.
| Inventors:
|
Goan; Kazuyoshi (Hino, JP)
|
| Assignee:
|
Konica Corporation (JP)
|
| Appl. No.:
|
151160 |
| Filed:
|
September 10, 1998 |
Foreign Application Priority Data
| Current U.S. Class: |
430/567; 430/603; 430/611; 430/966 |
| Intern'l Class: |
G03C 001/035; G03C 001/09 |
| Field of Search: |
430/567,603,611,966
|
References Cited
U.S. Patent Documents
| 5744296 | Apr., 1998 | Ishikawa et al. | 430/567.
|
| 5807663 | Sep., 1998 | Funakubo et al. | 430/567.
|
| 5851753 | Dec., 1998 | Yamada et al. | 430/603.
|
Primary Examiner: Huff; Mark F.
Attorney, Agent or Firm: Bierman; Jordan B.
Bierman, Muserlian and Lucas
Claims
What is claimed is:
1. A silver halide light sensitive photographic material comprising a
support having thereon hydrophilic colloid layers including a silver
halide emulsion layer, wherein (i) at least 50% of the total projected
area of silver halide grains contained in the emulsion layer is accounted
for by tabular grains having an aspect ratio of 3 to 15, (ii) said tabular
grains each comprising an inner region which accounts for 70% by volume of
the grain and a residual outer region, said outer region containing at
least 75% of total iodide contained in the grain, and (iii) said tabular
grains each having an outermost layer, a halide content distribution among
the tabular grains with respect to the outermost layer being not more than
20%; and wherein at least one of the hydrophilic colloid layers contains a
sulfur containing compound, which has a water-solubilizing group.
2. The silver halide photographic material of claim 1, wherein in (iii),
said halide content is an iodide content.
3. The silver halide photographic material of claim 2, wherein said
outermost layer contains is 0.1 to 10 mol % iodide.
4. The silver halide photographic material of claim 3 wherein said
outermost layer contains 0.1 to 5 mol % iodide.
5. The silver halide photographic material of claim 1, wherein said
outermost layer further contains at least 20 mol % bromide.
6. The silver halide photographic material of claim 5 wherein said
outermost layer contains at least 50 mol % bromide.
7. The silver halide photographic material of claim 1, wherein said sulfur
containing compound is represented by the following formula (1) or (2):
R.sup.1 --(S)m--R.sup.2 formula ( 1)
wherein R.sup.1 and R.sup.2 each represent an aliphatic hydrocarbon group,
an aromatic hydrocarbon group or a heterocyclic group, provided that at
least one of R.sup.1 and R.sup.2 has a water-solubilizing group and
R.sup.1 and R.sup.2 may combine with each other to form a ring; and m is
an integer of 2 to 6,
R--S(M)y formula (2)
wherein R represents an aliphatic hydrocarbon group, aromatic hydrocarbon
group or heterocyclic group or an atomic group, each of which has a
water-solubilizing group; M represents a hydrogen atom, an alkali metal
atom or a cationic group; and y is 0 or 1, provided that when y is 0, the
formula represents R.dbd.S, in which S is linked by a double bond to a
carbon atom contained in the R.
8. The silver halide photographic material of claim 7 wherein said
hydrophilic layers are on both sides of said support.
9. The silver halide photographic material of claim 8 wherein said sulfur
containing compound is contained in said emulsion layer.
10. The silver halide photographic material of claim 1, wherein said sulfur
compound is contained in the silver halide emulsion layer.
11. The silver halide photographic material of claim 1 wherein said
hydrophilic layers are on both sides of said support.
12. The silver halide photographic material of claim 11 wherein said
outermost layer contains at least 50 mol % bromide and 0.1 to 5 mol %
iodide.
13. The silver halide photographic material of claim 1 wherein there are at
least two distributions of halides in said outermost layer wherein each
are a maximum of 20%.
14. The silver halide photographic material of claim 1 wherein said silver
halide grains comprise silver iodobromide, silver iodochloride, or silver
iodochlorobromide.
15. The silver halide photographic material of claim 1 wherein a width of
grain size distribution is a maximum of 15%.
16. The silver halide photographic material of claim 15 wherein a width of
grain thickness distribution is a maximum of 20%.
17. The silver halide photographic material of claim 1 wherein said sulfur
containing compound is incorporated into the emulsion layer or a
non-emulsion layer.
Description
FIELD OF THE INVENTION
The present invention relates to a silver halide light sensitive
photographic material with superior processability even when subjected to
super-rapid access processing at a low replenishing rate, and a process
for forming X-ray photographic images.
Recently, with regard to processing of silver halide light sensitive
photographic materials, there have been demands for further reduction of
the processing time.
In the field of medical use, for example, the amount of time for X-ray
photographing is rapidly increasing due to increased use of X-rays for
diagnosis and inspection in general medical examinations, as well as
increased popularity of periodical health check-ups and clinical surveys,
and the result thereof must be made known as promptly as possible. There
is also increased use of arteriography and radiography during surgical
operation, in which rapid photographic processing is essential. To satisfy
such demands in the area of the diagnosis, it is necessary to promote
automation and the enhancing speed of radiographing and processing
operation of the light sensitive photographic materials.
Recently, reduced replenishment to processing solutions is also strongly
desired. From the view point of environment protection, low replenishment
has been advanced to reduce effluents from processing tanks. Especially,
disposal of industrial waste in the oceans has been prohibited since 1955
and such trends have become stronger.
In response to demands for rapid access and low-replenishment, it is
necessary to tackle these needs as a total system including the
photographic material, the processing solution and the processing
apparatus. In particular, development of photographic materials to be
processed is specifically important.
When subjected to rapid processing, conventional photographic materials led
to markedly increase fog and reduced sensitivity, which were not
acceptable in practical use.
To solve problems regarding the fog increase and sensitivity reduction, the
surface state of silver halide grains is of importance and there have been
made a large number of studies thereof. JP-A 3-237451 (herein, the term,
JP-A is referred to as unexamined, published Japanese Patent Application)
discloses silver halide grains which have a higher iodide content on the
surface than in the interior, achieving uniform adsorption of sensitizing
dyes and leading to a silver halide emulsion with enhanced sensitivity and
improved storage stability. However, the halide composition among grains
is not taught therein.
Uniformity among grains is also important and there have also been made a
number of studies thereof. JP-A 60-254032 discloses grains comprised of a
core containing iodide of 5 mol % or more and a shell containing less
iodide and an emulsion with a relative standard deviation of iodide
contents among grains of 20% or less, thereby achieving high sensitivity,
high contrast and superior graininess. However, there is taught nothing
with respect to halide composition of the outermost surface of the grains.
To enhance the developing rate or fixing rate, it is preferable to reduce
the silver iodide content of silver halide grains. The reduced silver
iodide content on the surface of silver halide grains results in
deterioration of adsorption of a spectral sensitizing dye, leading to a
lowering of spectral sensitivity or an increase of pressure fog.
Reduction of the coating weight of silver is advantageous in terms of
low-replenished processing, so that it is essential to obtain a higher
density with a given silver coverage. That is, silver halide grains with a
large covering power are needed. To meet this need, it is desirable to
employ silver halide grains of a smaller size or tabular silver halide
grains with a larger projection area. To employ the silver halide grains
of a smaller size, efficient sensitization is needed. The tabular silver
halide grains are also preferred in terms of spectral sensitization
efficiency or sensitivity.
Recently, techniques for enhancing sensitivity and image quality by the use
of tabular silver halide grains were disclosed in JP-A 58-111935,
58-111936, 58-111937, 58-113927 and 59-99433. Further, JP-63-92942
discloses a technique for providing a core with a high silver iodide
content in the interior of tabular silver halide grains, and JP-A
63-151618 discloses a technique of employing hexagonal tabular silver
halide grains, showing effects of enhancing sensitivity. Furthermore, JP-A
63-106746, 1-183644 and 1-279237 disclose techniques regarding to halide
composition of tabular silver halide grains.
However, the tabular silver halide grains have a disadvantage such that
pressure resistance characteristics are deteriorated. In general, silver
halide grains are sensitive to pressure, and the higher the sensitivity,
the more sensitive to pressure, in particulat, the tabular silver halide
grains are marked to a noticeable extent. It is reasoned that tabular
grains are thinner than a spherical grains with an equivalent volume so
that the tabular grains are easily subjected to larger moments and the
grains become overall weaker in mechanical strength.
Pressure characteristics depend on conditions of chemical sensitization of
the silver halide grains, as well as the grain shape. It is generally
known that when the extent of chemical sensitization is insufficient,
pressure desensitization is marked; and when the extent of chemical
sensitization is excessive, the pressure desensitization is small but
pressure fog increases. Specifically, when the tabular grains are
subjected to excessive chemical sensitization, problems often occur such
as increased pressure fog. Furthermore, when a spectral sensitizing dye is
adsorbed thereto, marked pressure fog due to chemical sensitization tends
to occur. There have been studies of selenium sensitization and/or
tellurium sensitization for enhancing sensitivity, and when these
sensitization are applied, the pressure fog also tends to increase.
Accordingly, the tabular silver halide grains are desired to enhance
pressure resistance characteristics and lowering pressure fog. There have
been a number of studies regarding enhancing pressure resistance
characteristics. U.S. Pat. No. 2,628,167 discloses an emulsion containing
a thallium salt, thereby improving pressure desensitization and enhancing
sensitivity and contrast. Although there is no description with respect to
pressure fog, a technique of lowering pressure fog is, in general, to
accelerate pressure desensitization so that the technique disclosed is
anticipated to increase pressure fog. There are also disclosed means for
enhancing pressure resistance characteristics in JP-A 59-994333, 60-35726,
60-147727, 63-301937, 63-149641, 63-106746, 63-151618, 63-220238,
1-131541, 2-193138, 3-172836, 3-231739, 6-266032 and 6-324418, but these
means did not achieve sufficient improvements.
Specifically, with regard to spectrally sensitized tabular silver halide
grains or selenium/and or tellurium sensitized tabular silver halide
grains, an effective means for lowering pressure fog has not yet been
found. Further, since there is an antinomy relationship such that a
technique of lowering pressure fog is, in general, to accelerate pressure
desensitization, it has been difficult to develop a technique for
satisfying both needs. Another disadvantage of the tabular grains concerns
deterioration of silver color tone. As the grain thickness of silver
halide grains decreases, scattering of the blue light component due to
filamentary silver formed on development increases, resulting in yellowish
transmitted light and silver images becoming yellowish. The color of
silver images is called as silver image tone (or color). In photographic
materials for medical use, a yellowish silver image tone is not preferred
and therefore, development of silver halide grains which are of tabular
form and superior in silver image tone, has been desired.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a silver halide light
sensitive photographic material superior in rapid processability even when
processed at a low replenishment rate and with low fog and high
sensitivity.
Another object is to provide a method of forming an X-ray image by
processing the silver halide photographic material having such
capabilities as described above, through a rapid access which is safe and
meeting environmental restrictions.
The above objects of the present invention can be attained by the following
constitution:
(1) A silver halide light sensitive photographic material comprising a
support having thereon hydrophilic colloid layers including a silver
halide emulsion layer, wherein (i) at least 50% of the total projected
area of silver halide grains contained in the emulsion layer is accounted
for by tabular grains having an aspect ratio of 3 to 15, (ii) said tabular
grains each comprising an inner region which accounts for 70% by volume of
the grain and a residual outer region, said outer region containing at
least 75% of the total iodide contained in the grain, and (iii) said
tabular grains each having an outermost layer, a halide content
distribution among the tabular grains of the outermost layer being not
more than 20%; and wherein at least one of the hydrophilic colloid layers
contains a sulfur containing compound which has a water-solubilizing
group.
(2) The silver halide photographic material described in (1), wherein the
sulfur containing compound having a water-solubilizing group is
represented by the following formula (1) or (2):
R.sup.1 --(S)m--R.sup.2 formula (1)
wherein R.sup.1 and R.sup.2 each represent a substituted or unsubstituted
aliphatic group, aromatic group or heterocyclic group, provided that at
least one of R.sup.1 and R.sup.2 has a water-solubilizing group and
R.sup.1 and R.sup.2 may combine with each other to form a substituted or
unsubstituted ring, and R.sup.1 and R.sup.2 may the same or different; and
m is an integer of 2 to 6,
R--S(M)y formula (1)
wherein R represents an aliphatic hydrocarbon group, aromatic hydrocarbon
group or heterocyclic group, each of which has a water-solubilizing group;
S(M)y represents a group capable of being adsorbed to silver halide, M
represents a hydrogen atom, an alkali metal atom or a cationic group, and
y is 0 or 1, provided that when y is 0, the formula represents R=S, in
which S is linked by a double bond to a carbon atom contained in the R.
(3) The silver halide photographic material described in (1) or (2),
wherein the sulfur compound having a water-solubilizing group is contained
in the silver halide emulsion layer.
(4) The silver halide photographic material described in any one of (1),
(2) and (3), wherein the silver halide photographic material has silver
halide emulsion layers on both sides thereof.
DETAILED DESCRIPTION OF THE INVENTION
The halide content distribution among grains with respect to the outermost
layer concerns halide(s) other than a halide the content of which
(expressed in mol %) is maximum among halides contained in the outermost
layer. In the case of silver halide grains having the outermost layer
comprised of 60 mol % of silver chloride, 30 mol % of silver bromide and
10 mol % of silver iodide, for example, the bromide content distribution
among grains of the outermost layer and the iodide content distribution
among grains of the outermost layer are each defined. In cases where two
or more halide contents of the outermost layer are defined in a single
emulsion, the distribution of at least one of the two or more halide
contents, among grains, is 20% or less; and preferably, distributions of
two or more halide contents among grains are each 20% or less. The
distribution among grains is preferably 12% or less, more preferably 10%
or less, and still more preferably 5% or less. Herein, the halide content
distribution among grains is defined as standard deviation of the halide
content among grains divided by the average halide content of grains times
100%.
In silver halide grains according to the invention, at least 50% of the
total grain projected area is accounted for by grains having a silver
halide layer containing at least 75% (preferably, at least 80%) of the
total iodide contained in the grain within the outer region other than the
inner region corresponding to 70% by volume, based on the grain. Further,
the outermost surface layer preferably contains silver bromide. The silver
bromide content of the outermost surface layer is preferably not less than
20 mol %, and more preferably not less than 50 mol %. The outermost
surface preferably contains silver iodide of 0.1 to 10 mol %, more
preferably 0.5 to 5 mol %, and still more preferably 1.0 to 5 mol %.
The silver halide grains according to the invention preferably contain a
silver bromide and/or silver iodide localizing phase, in the vicinity of
the surface and/or in the vicinity of the corner of the grain. The
expression "in the vicinity of the surface" means the position within a
depth of 1/5 of the grain size (preferably 1/7) from the surface.
The silver bromide localizing phase in the vicinity of the surface and/or
in the vicinity of the corner, preferably contains not less than 20 mol %
silver bromide, and more preferably not less than 50 mol % silver bromide.
The silver iodide localizing layer preferably contains 0.1 to 5 mol %
silver iodide.
The halide composition of the outermost surface layer can be determined by
a means generally called surface electron spectroscopy such as Auger
electron spectroscopy, X-ray photoelectron spectroscopy, or ion scattering
spectroscopy, or secondary ion mass spectrometry (hereinafter, also
denoted as SIMS). In the invention, in order to determine the halide
composition distribution, it is necessary to have spatial resolving power
to the extent capable of discriminating each grain. The extent capable of
discriminating each grain means that the spatial resolving power of a
detecting means is preferably not more than 0.5 of the average diameter of
silver halide grains as the object, more preferably not more than 0.2, and
still more preferably not more than 0.1. In cases where the detecting
probe is a charged particle such as an electron or ion, the spatial
resolving power can be enhanced by convergence with a lens. In the case of
X-rays, cyclotron radiation ray can be employed by reference to B. M.
Gordon and B. Manowitz, US DOE Rep. BNL-46377 (1991). The surface electron
spectroscopy is referred to D. Briggs and M. P. Shear "Surface Analysis,
Basis and Application" and the ion scattering spectroscopy is referred to
L. M. Niedzwiecki and Y. T. Tan, J. Photogr. Sci. 35, 155 (1987). The
Auger electron spectroscopy, X-ray photoelectron spectroscopy and ion
scattering spectroscopy are referred to Okusa et al. "Surface Analysis of
Silver Halide Microcrystals by Photoelectron Spectroscopy" (Proceedings of
IS$T's 47th Annual Conference/May 1994/Rochester N.Y.), in which the
measured object needs to be cooled to prevent alteration of silver halide
grains during measurement.
The SIMS is a form of destruction analysis so that the measured object need
not necessarily be cooled, but in the measurement of the outermost surface
layer, the total ion doping amount is indispensable to be
2.times.10.sup.13 particles/cm.sup.2 or less. Furthermore, as disclosed in
"Secondary Ion Mass Spectrometry SIMS VII" p.821, 1990 (John Wiley &
Sons), it is necessary to provide a multi-channel detecting system which
can simultaneously measure plural kinds of the secondary ions ejected from
portions destroyed by the primary ions. It is not preferable to employ a
single-channel detecting system, as disclosed in T. J. Maternaghan et al.,
J of Imag. Sci. 34, 58 (1990). In light of the foregoing, the most
preferable SIMS usable in the present invention is Time of Flight type
Secondary Ion Mass Spectrometry (hereinafter, also denoted as TOF-SIMS).
Halide composition of the outermost surface layer of silver halide grains
can be measured using TOF-SIMS in accordance with the following procedure.
In the invention, the halide composition of the outermost surface layer of
silver halide grains is one measured in the following manner. Thus, to
take out silver halide grains from a silver halide emulsion, in general,
the emulsion is treated with proteinase under a safelight to degrade the
gelatin used as a dispersing medium, and after centrifuging, the
supernatant solution is decanted and washed with distilled water. In cases
where silver halide grains are present in a coating layer with a gelatin
binder, the gelatin is similarly degraded with proteinase to take out the
grains. In cases where a polymer other than gelatin is contained, the
polymer can be leached out by using an appropriate organic solvent. In the
case of a dyestuff or a sensitizing dye adsorbed onto the grains, these
materials can be removed by using an aqueous alkaline solution or an
alcohol. The grains dispersed in water is coated on a conductive substrate
and dried to be subjected to measurement. It is preferable to arrange the
grains without allowing coagulation and it is also preferable to confirm
samples obtained according to a series of procedure by optical microscopic
or electron microscopic observation. A dispersing aid may be employed to
prevent grain coagulation. In this case, generally used anionic
surfactants or cationic surfactants are not preferable because theu tend
to make the secondary ion strength unstable in the SIMS measurement. An
aqueous solution containing gelatin of 0.2% by weight or less is
preferably employed. Preferably used is a conductive substrate with a
smooth surface which contains no element having a high secondary ion
yield, such as an alkaline metal. A mirror polished silicon monocrystal
wafer with a low resistivity of 1.0 .OMEGA..multidot.cm is preferably
employed. A rotary coater or a freeze-dry lyophilizer is optimally
employed to arrange the grains on the substrate without causing
coagulation.
Preferred ion species used as the primary ion in the TOF-SIMS measurement
include liquid metal ion species such as Au.sup.+, In.sup.+, Cs.sup.+ and
Ga.sup.+, the preferred one of these being Ga.sup.+. The secondary ion to
be detected is a univalent anion. With respect to silver chloride, silver
bromide and silver iodide, 35Cl.sup.-, 37Cl.sup.-, 79Br.sup.-, 81Br.sup.-
and 127I.sup.- are respectively measured.
The primary ion accelerating voltage is preferably between 20 kV and 30 kV
and subjected to various adjustments so that the beam diameter measured by
the knife edge method is 0.25 .mu.m or less. Exposing conditions such as a
beam current and an exposure time are optional, but it is preferable that
the total primary ion doping amount is not more than 2.times.10.sup.13
particles/m.sup.2. The primary beam scanning region is optional, and it is
preferable to measure the secondary ion strength on each point on the
grain surface at an interval of 0.2 .mu.m or less. For example, when
scanning a region of 20 .mu.m.times.20 .mu.m, measurement is made so as to
obtain values at 128 points.times.128 points. When completing the
measurement, the sample is moved to such a position that the beam scanning
region is not overlapped and measurement is similarly repeated until
completing the measurement of at least 50 grains which are arranged on the
substrate without coagulating or contacting with each other. The thus
obtained data can be recorded as an arrangement of each of the measuring
regions with respect to each of the secondary ions.
The arrangement obtained by the measurement described above is subjected to
objective treatment using an appropriate spreadsheet program. Arrangement
A representing the number of secondary ions of 35Cl.sup.-, 37Cl.sup.-,
79Br.sup.-, 81Br.sup.- and 127I.sup.-, which are obtained in a single
measuring region, that is, A(35Cl.sup.-), A(37Cl.sup.-), A(79Br.sup.-),
A(81Br.sup.-) and A(127I.sup.-) are converted to Arrangement B
representing the sum of univalent secondary ions of CL.sup.-, Br.sup.-
and I.sup.-, that is,
B(Cl)=A(35Cl.sup.-)+A(37Cl.sup.-)
B(Br)=A(79Br.sup.-)+A(81Br.sup.-)
B(I)=A(127I.sup.-)
Then, according to the following relationship, Arrangement C can be
obtained, representing two-dimensional distribution of the outermost
surface silver chloride content, the outermost surface silver bromide
content and the outermost surface silver iodide:
C(AgCl%)=100.times.B(Cl)/[B(Cl)+B(Br)+B(I)]
C(AgBr%)=100.times.B(Br)/[B(Cl)+B(Br)+B(I)]
C(AgI%)=100.times.B(I)/[B(Cl)+B(Br)+B(I)].
The value of each element in the Arrangement is converted to gray scale or
color and two-dimensionally represented.
Next, for making correction of phenomenon in which the primary ion beam has
a spatial strength distribution and the secondary ion yield is lowered in
the surrounding of the grain, a critical value of 50 to 100 counts is
defined in the arrangement having a maximum sum of arrangement elements
among Arrangement B; from the arrangement elements, one not reaching the
critical value is selected; and operation of making zero the corresponding
Arrangement C is made to determine new Arrangement C'. The Arrangement C'
is an arrangement representing two-dimensional distribution of the
outermost surface halide content. Thus, the outermost surface halide
content of silver halide grains can be obtained by averaging elements
having a value other than zero and forming a group including a hexagon, a
triangle, a circle, a square and a rectangle. Similarly, the outermost
surface halide contents of at least 50 silver halide grains is determined,
and from the average value and standard deviation of the grains, a
coefficient of variation (or C.V. value) can be obtained to determine the
halide composition distribution among the grains.
In the silver halide emulsion according to the invention is employed silver
iodobromide, silver iodochloride or silver iodochlorobromide. In the case
when tabular silver halide grains according to the invention have (111)
major faces, the silver bromide content is preferably 50 mol % or more. In
the case when having (100) major faces, the silver chloride content is
preferably 30 mol % or more.
The halide composition of each grain and an average halide composition of
overall grains can be determined by means of EPMA (Electron Probe Micro
Analyzer). In this method, a sample which is prepared by dispersing silver
halide grains so as not to be in contact with each other, is exposed to an
electron beam to conduct X-ray analysis by excitation with the electron
beam. Thereby, elemental analysis of a minute portion can be done. Thus,
halide composition of each grain can be determined by measuring
intensities of characteristic X-ray emitted from each grain with respect
to silver and iodide. At least 50 grains are subjected to the EPMA
analysis to determine their iodide contents, from which the average iodide
content can be determined.
It is preferred that the silver halide tabular grains according to the
invention have uniformly iodide contents among grains. When the iodide
content of grains is determined by the EPMA analysis, a relative standard
deviation thereof (i.e., a variation coefficient of the iodide content of
grains) is 35% or less, preferably, 20% or less.
In the silver halide emulsion according to the invention, tabular silver
halide grains account for at least 50% of the total projected area of
silver halide grains contained in the emulsion, and more preferably 70% or
more, still more preferably 80 to 100%, and most preferably 90 to 100% is
tabular grains. The tabular silver halide grains refers to those having
two parallel major faces and a ratio of the grain diameter to the grain
thickness (hereinafter, also denoted as an aspect ratio) of 3 or more. The
grain diameter is its equivalent circular diameter (i.e., the diameter of
a circle having an area equivalent to the projected area of the grain).
The grain thickness is referred to as a distance between two parallel
major faces. The average aspect ratio of the tabular silver halide grains
contained in the silver halide emulsion according to the invention is
preferably not less than 3 and not more than 15, more preferably not less
than 3 and less than 10, still more preferably not less than 3 and less
than 8, and most preferably not less than 3 and less than 5.
The major faces of the tabular silver halide grains according to the
invention may be (111) faces or (100) faces. In cases where the major
faces are comprised of (111) faces, the tabular silver halide grains are
preferably hexagonal. The hexagonal tabular silver halide grains
(hereinafter, sometimes, referred to as hexagonal tabular grains) have
hexagonal major faces ((111) faces), and having a maximum adjacent edge
ratio of 1.0 to 2.0. The expression, "maximum adjacent edge ratio" is
referred to as a ratio of a maximum length of edges constituting the
hexagon to a minimum edge length. In the invention, if the hexagonal
tabular silver halide grains have a maximum adjacent edge ratio of 1.0 to
2.0, the corner of the grain may be roundish. In the case of being
roundish, the edge length is defined as a distance between crossing points
of an extended straight line of the edge and that of an adjacent edge. The
corner may disappear, resulting in round grains. It is preferred that 1/2
or more of each edge of the hexagonal tabular grains is substantially
straight. The a maximum adjacent edge ration is preferably 1.0 to 1.5.
In case where the major faces is comprised of (111) faces, the tabular
silver halide grain according to the invention preferably contain two or
more twin planes parallel to the major faces. The twin plane can be
observed by a transmission electron microscope. Thus, a sample is prepared
by coating a silver halide emulsion so that the major faces of the tabular
grains contained are oriented substantially in parallel to the support.
The sample is cut using a diamond cutter to obtain a slice with about 0.1
.mu.m thick. The presence of the twin plane can be confirmed by observing
the slice by a transmission electron microscope.
A spacing between twin planes according to the invention is defined as
follows. In the case when the twin planes are two, the spacing between
twin planes is a distance between the two twin planes. In the case of
three or more twin planes, the pacing between twin planes is the longest
distance between twin planes. The spacing between twin planes can be
determined according to the following manner. Thus, 100 tabular grains
exhibiting section perpendicular to the major faces are selected through
transmission electron microscopic observation of the slice and the twin
plane spacing of each grain is measured to obtain an average thereof. The
average twin plane spacing is preferably not less than 0.008 .mu.m, more
preferably not less than 0.010 .mu.m, and still more preferably not less
than 0.012 .mu.m and not more than 0.05 .mu.m.
In the case of the major faces comprising (100) faces, the major faces of
tabular silver halide grains are in the form of a rectangle or one with
rounded corners. An adjacent edge ratio of the rectangle is preferably
less than 10, more preferably less than 5, and still more preferably less
than 2. The edge length of the rectangle with rounded corners is a length
to a crossing point between extension of a straight portion of an edge of
the rectangle and that of a straight portion of an adjacent edge. The
method of measuring crystal faces of tabular silver halide grains is
referred to Tani et al. J. Imag. Sci 29 [5] Sept. 1985.
The tabular silver halide grains may contain dislocation. The dislocation
can be directly observed by using a transmission electron microscope at a
low temperature, as described in J. F. Hamilton, Phot. Sci. Eng., 57
(1967) and Shiozawa, J. Soc. Phot. Sci. Japan, 35, 213 (1972). Thus,
silver halide grains which are taken out from an emulsion without applying
pressure in an extent of causing dislocation within the grain, are placed
on a mesh for use in electronmicroscopic observation and observed by a
transmission electron microscope under cooling conditions for preventing
damage due to the electron beam (e.g., print-out). In view of the fact
that the thicker the grain is, the harder transmission of the electron
beam becomes, the use of a high voltage type (i.e., 200 kV or more per
0.25 .mu.m in grain thickness) electron microscope is preferred for
definite observation.
The average grain diameter of silver halide grains relating to the
invention is preferably 0.15 to 5.0 .mu.m, more preferably 0.4 to 3.0
.mu.m, and still more preferably 0.4 to 2.0 .mu.m. The average grain
thickness of silver halide grains relating to the invention is preferably
0.01 to 1.0 .mu.m, more preferably 0.02 to 0.40 .mu.m, and still more
preferably 0.02 to 0.30 .mu.m.
The tabular silver halide grains are preferably monodispersed. In other
words, a width of grain size distribution is preferably 25% or less, more
preferably 20% or less, still more preferably 17% or less, and most
preferably 15% or less. The width of the grain size distribution is
defined in a relative standard deviation (variation coefficient) of the
grain diameter, which is expressed as;
(standard deviation of grain diameter/average grain
diameter).times.100=width of grain size distribution (%).
It is also preferred that the tabular silver halide grains be small in
grain thickness distribution. In other words, a width of grain thickness
distribution is preferably 30% or less, more preferably 25% or less, and
still more preferably 20% or less. The width of the grain thickness
distribution is defined in a relative standard deviation (variation
coefficient) of the grain thickness, which is expressed as:
(standard deviation of grain thickness/average grain
thickness).times.100=width of grain thickness distribution (%).
The grain diameter and grain thickness can be optimized so as make
photographic characteristics such as sensitivity best. The optimum grain
diameter and thickness each depend on other factors constituting the
photographic material (e.g., thickness of a hydrophilic colloid layer,
degree of hardening, chemical ripening conditions, designed speed of a
photographic material, silver coverage).
To obtain the silver halide emulsion according to the invention, it is
necessary to enhance uniformity among grains of the surface halide
composition. Enhancement of the uniformity among grains of the outermost
surface halide composition can be performed at any step of the process of
manufacturing a silver halide photographic material, including silver
halide grain growth, chemical ripening, coating solution preparation and
coating, and preferably at the step from immediately before completing the
grain growth to immediately after completing the chemical ripening.
When addition of a silver halide fine grain emulsion is applied in the
present invention, the fine grain size is preferably not more than 0.15
.mu.m, more preferably not more than 0.1 .mu.m, and still more preferably
not more than 0.06 .mu.m. The fine grain emulsion is added preferably at a
temperature of 30 to 80.degree. C., and more preferably 40 to 65.degree.
C.
The process of preparing the silver halide emulsion according to the
invention will now be explained. The process of preparing the silver
halide emulsion containing tabular silver halide grain with (111) major
faces comprises preferably the nucleation step, the ripening step and the
grain growth step. At any step of after completing nucleation, during or
after ripening and during grain growth, it is preferred to interrupt the
grain preparation, use formed silver halide grains as seed grains and
deposit silver halide on the surface of the seed grains to grow grains.
For example, in a process of preparing a silver halide emulsion by
supplying aqueous silver salt and halide solutions in the presence of a
dispersing medium solution to obtain a silver halide emulsion containing
tabular grains with (111) major faces, the process preferably comprises:
(i) a nucleation step, in which the pBr of mother liquor is maintained at
0.7 to 2.5 during a period of from the start of forming silver halide
containing 0 to 5 mol % iodide to 1/2 or more;
(ii) subsequently to the nucleation step, a seed grain forming step, in
which a silver halide solvent is contained in the mother liquor in an
amount of 10-5 to 2.0 mol per mol of silver halide to form substantially
monodispersed silver halide spherical twinned crystal grains, or a seed
grain forming step, in which after nucleation, the temperature of the
mother liquor is raised to 40 to 80.degree. C. to form silver halide
twinned crystal seed grains; and
(iii) a crystal grain growth step, in which aqueous silver salt and halide
solutions and/or a silver halide fine grain emulsion are further added to
grow the seed grains. In this case, the mother liquor is a solution
employed in preparation of the silver halide emulsion including a final
silver halide emulsion.
During the seed grain formation step, an aqueous silver salt solution may
be added for the purpose of adjusting the ripening. The grain growth step
of growing silver halide seed grains can be achieved by controlling the
pAg, pH, temperature, concentration of the silver halide solvent, silver
halide composition and flow rates of silver salt and halide solutions
during silver halide precipitation. known silver halide solvents such as
ammonia, thioethers and thioureas can be made present in the steps of seed
grain formation and grain growth.
As disclosed in JP-A 51-39027, 55-142329, 58-113928, 54-48521 and 58-49938,
the tabular silver halide grain according to the invention can be obtained
by growing the formed seed grains under the condition that an aqueous
soluble silver salt solution and a halide solution are added by the double
jet method at a flow rate which is gradually varied in proportion to grain
growth without forming a new nucleus and widening the grain size
distribution, that is, within a range of 30 to 100% of the rate of causing
new nuclei to form.
In preparation of the silver halide emulsion containing tabular grains with
(100) major faces, nucleation can be performed under conditions that (100)
faces are easily formed, for example, in the presence of an iodide ion or
at a low pCl. After nucleation, Ostwald ripening and/or growth are
performed to obtain tabular silver halide grains with an intended size and
its distribution. Thus, in one preferred embodiment, a silver salt
solution, a halide solution containing iodide and a protective colloid
solution are added to a first vessel to form nucleus grains, and after
nucleus grain formation, the mixture solution is transferred to a second
vessel and grain growth is performed therein. In this case, the growth is
interrupted and using the formed grain as seed grains, silver halide may
be deposited on the seed grains. Thus, to a vessel containing a protective
colloid solution and seed grains, silver ions, halide ions and optionally
fine silver halide grains are supplied thereto to grow the seed grains.
There is also applicable a process of preparing a silver halide emulsion,
comprising the steps of 1) adding a silver salt in the absence of an
iodide to start nucleation and 2) subsequently, adding a silver salt in
the presence of an iodide to perform nucleation and/or crystal growth, as
described in JP-A 9-5909. Thus, the process comprises any one of (a)
starting nucleation in the absence of an iodide and subsequently,
performing nucleation in the presence of an iodide; (b) starting
nucleation in the absence of an iodide and subsequently, performing
crystal growth in the presence of an iodide; and (c) starting nucleation
in the absence of an iodide and subsequently, performing simultaneously
nucleation and crystal growth in the presence of an iodide. In any case,
the iodide is not present at the start of nucleation and immediately
thereafter, the iodide is made present. Furthermore, there is also
applicable a preparation process in which the iodide is not allowed to be
present during nucleation and/or immediately thereafter.
Each of the steps is further described in detail.
(1) Nucleation:
To a dispersing medium solution containing a dispersing medium and water
were added with stirring silver salt and/or halide solutions to form
nucleus grains. The pCl at the start of nucleation is adjusted to 0.5 to
3.5, preferably 1.0 to 3.0, and more preferably 1.5 to 2.5 so as to
promote formation of (100) faces. An iodide can be introduced until
reached solid solubility of silver iodide and silver chloride. The iodide
concentration of the protective colloid solution at the start of
nucleation is preferably not more than 10 mol %, more preferably 0.001 to
10 mol %, and still more preferably 0.05 to 10 mol %. A bromide ion may be
present in the protective colloid solution at the start of nucleation, as
far as not less than 20 mol % of a chloride ion are present therein. The
pH is preferably not less than 1.0, more preferably not less than 1.5, and
still preferably 2.0 to 8.0. Gelatin and its derivatives are employed as a
dispersing medium, and impurity-free gelatin is preferably employed. Of
these is preferably employed a low methionine containing gelatin with a
content of less than 30 .mu.mol/g gelatin, and preferably less than 15
.mu.mol/g gelatin. A low molecular weight gelatin is preferably employed,
having a molecular weight of 1,000 to 10.times.10.sup.4, and preferably
2,000 to 6.times.10.sup.4. Gelatin is employed singly or in combination
with another kind of gelatin. The dispersing medium concentration is
preferably 0.1 to 10% by weight, and more preferably 0.3 to 5% by weight.
The addition time of the silver salt solution at nucleation is preferably
not less than 5 sec. and less than 1 min., and in the mean while, another
kind of a halide may be added thereto. Thus, only a silver salt may be
added by the single jet addition, or silver salt and halide solutions may
be added by the double jet addition. The temperature is preferably 30 to
90.degree. C., and more preferably 35 to 70.degree. C. The silver amount
to be added at nucleation is preferably 0.1 to 10 mol %, based on the
total silver.
(2) Ripening:
The process of preparing the silver halide emulsion according to the
invention, preferably comprises the step of ripening, sebsequent to the
nucleation step. In the ripening step, tabular grains produced at the
nucleation step are allowed to grow and other grains allowed to disappear
through Ostwald ripening. The ripening temperature is preferably 20 to
90.degree. C., more preferably 30 to 85.degree. C. and still more
preferably 40 to 80.degree. C. The temperature at ripening may be kept
constantly or varied. The ripening temperature is preferably varied, and
more preferably raised. The pCl at ripening is preferably 0.5 to 3.5, and
more preferably 1.0 to 3.0. The pH at ripening is preferably 1 to 12, more
preferably 2 to 8, and still more preferably 2 to 6. Ripening is performed
preferably in the absence of a silver halide solvent, such as ammonia.
(3) Crystal growth:
The process can further comprises the step of crystal growth, subsequent to
the ripening step. The pCl at crystal growth is adjusted to the range of
0.5 to 3.5, preferably 1.0 to 3.0, and more preferably 1.5 to 2.5. The pH
is preferably 1 to 12, more preferably 2 to 8, and still more preferably 2
to 6. The temperature at crystal growth is preferably 40 to 90.degree. C.,
more preferably 45 to 80.degree. C., and still more preferably 50 to
75.degree. C. Addition of a silver ion and halide ion is performed by the
double jet method of adding silver salt and halide sooution, the fine
grain supplying method of adding previously prepared fine silver halide
grain emulsion, or by their combined method. Of these is preferred the
fine grain supplying method. In this case, The fine grain size is
preferably 0.15 .mu.m or less, more preferably 0.1 .mu.m or less, and
still more preferably not more than 0.06 .mu.m or less.
The growth is interrupted in the course of the growth step and the formed
grains, as seed grains are futher grown by depositing silver halide on the
seed grains. Thus, to a reactionvessel containing a dispersing medium and
seed grains are supplied silver salt and halide solutions or optionally a
fine silver halide grain emulsion to allow the seed grains to grow. In the
process of preparing a silver halide emulsion according to the invention
can be present known silver halide solvents such as ammonia, thioethers
and thiourea.
In the process of preparing the silver halide emulsion according to the
invention, silver halide grains with an intended size and its distribution
can be obtained by growing grains under the condition that an aqueous
soluble silver salt solution and a halide solution are added by the double
jet method at a flow rate which is gradually varied in proportion to grain
growth without forming a new nucleus and widening the grain size
distribution due to Ostwald ripening, that is, within a range of 30 to
100% of the rate of forming new nuclei. Another process disclosed in
Abstract, item 88 of Annual Meeting of Society of Photographic Science and
technology of Japan is also preferable, in which a fine silver halide
grain emulsion is added, dissolved and recrystalized to grow grains. In
this case, fine silver iodide grains, fine silver bromide grains, fine
silver iodobromide grains, fine bromochloride grains or fine silver
chloride grains are preferred.
Silver halide grains relating to the invention may be so-called halide
conversion type grains. The halide conversion amount is preferably 0.2 to
5 mol %, based on the silver amount. The conversion may be conducted
during or after physical ripening. An aqueous solution of a halide, of
which solubility product with silver is less than that of a halide
component on the surface of silver halide grains before subjected to
conversion, or corresponding fine silver halide grain emulsion, is
conventionally added. In the latter case, the fine grain size is
preferably 0.2 mm or less, and more preferably 0.02 to 0.1 .mu.m.
In the process of preparing the silver halide emulsion according to the
invention is of importance stirring conditions during the process. A
stirring apparatus disclosed in JP-A 62-160128 is preferred, in which a
liquid-introducing nozzle is submerged near an intake of the mother
liquor. The stirring rotation number is preferably 100 to 1200 rpm.
Details of the supersaturating factors described above are referred to
JP-A 63-92942 and 1-213637.
The compound represented by formula (1) is now further described. The
aliphatic group represented by R.sup.1 and R.sup.2 of formula (1) includes
a straight-chained or branched alkyl, alkenyl, alkynyl or cycloalkyl group
having 1 to 30 carbon atoms, and preferably 1 to 20 carbon atoms, such as
methyl, ethyl, propyl, butyl, hexyl, decyl, isopropyl, t-butyl,
2-ethylhexyl, allyl, 2-butenyl, 7-octenyl, propargyl, 2-butynyl,
cyclopropyl, cyclopentyl, cyclohexyl and cyclododecyl. The aromatic group
represented by R.sup.1 and R.sup.2 of formula (1) includes one having 6 to
20 carbon atoms, such as phenyl, naphthyl and anthranyl groups. The
heterocyclic group represented by R.sup.1 and R.sup.2 of formula (1) may
be monocyclic or condensed cyclic one, including a 5 or 6-membered
heterocyclic ring containing at least one of O, S and N atoms. Examples
thereof include pyrolidine, piperidine, tetrahydrofuran, tetrahydropyran,
oxirane, morphorine, thiomorphorine, furfuryl, thiopyrane,
tetrahydrothiophene, pyrrole, pyridine, furan, thiphene, imidazole,
pyrazole, oxazole, thiazole, isooxazole, isothiazole, triazole, tetrazole,
thiadiazole, oxadiazole, and their benzelogs. The ring formed by
combination of R.sup.1 and R.sup.2 includes 4 to 7-membered rings.
Preferable are 5 to 7-membered rings. Preferable R1 and R2 are each a
heterocyclic group, and more preferably an aromatic heterocyclic group.
The aliphatic group, aromatic group and hetocyclic group may be
substituted. Examples of substituents include a halogen atom (e.g.,
chlorine atom, bromine atom), an alkyl group (e.g., methyl, ethyl,
isopropyl, hydroxyethyl, methoxyethyl, trifluoromethyl, t-butyl), a
cycloalkyl group (e.g., cyclopentyl, cyclohexyl), an aralkyl group (e.g.,
benzyl, 2-phenethyl), an aryl group (e.g., phenyl, naphthyl, p-tolyl,
p-chlorophenyl), an alkoxy group (e.g., methoxy ethoxy, isoproxy,
n-butoxy), an aryloxy group (e.g., phenoxy), cyano group, an acylamino
group (e.g., acetylamino, propionylamino), an alkylthio group (e.g.,
methylthio, ethylthio, n-butylthio), an arylthio group (e.g., phenylthiol,
an sulfonylamino group (e.g., methanesulfonylamino, benzenesulfonylamino),
an ureido group (e.g., 3-methylureido, 3,3-dimethylureido,
1,3-dimethylureido), an sulfamoylamino group (e.g.,
dimethylsulfamoylamino), an carbamoyl group (e.g., methylcarbamoyl,
ethylcarbamoyl, dimethylcarbamoyl), a sulfamoyl group (e.g.,
ethylsulfamoyl, dimethylsulfamoyl), an alkoxycarbonyl group (e.g.,
methoxycarbonyl, ethoxycarbonyl), an aryoxycarbonyl group (e.g.,
phenoxycarbonyl), an sulfonyl group (e.g., methanesulfonyl,
butanesulfonyl, phenylsulfonyl), an acyl group (e.g., acetyl, propanoyl,
butyloyl) an amino group (e.g., methylamino, ethylamino, dimethylamino),
hydroxy, nitro, nitroso, an amineoxide group (e.g., pyridine-oxide), an
imido group (e.g., phthalimido), a disulfide group (e.g.,
benzenedisulfide, benzothiazolyl-2disulfide) and a heterocyclic group
(e.g., pyridyl, benzimidazolyl, benzthiazolyl, benzoxazolyl). m is an
interger of 2 to 6, preferably 2 to 5 and more preferably 2.
Further, at least one of R.sup.1 and R.sup.2 has a water-solubilizing
group. Examples of the water-solubilizing group include --SO.sub.3
M.sup.1, --COOM.sup.1, --OH, --NHR.sup.3 and a N-attached oxide group in
which M.sup.1 is a hydrogen atom, an alkali metal atom or a cation.
R.sup.3 represents a hydrogen atom, an alkyl group having 1 to 6 carbon
atoms, --COR.sup.4, --COOR.sup.4 or --SO.sub.2 R.sup.4, in which R.sup.4
represents a hydrogen atom, an aliphatic group or aromatic group as
defined in R.sup.1 and R.sup.2. Of these, --SO.sub.3 M.sup.1,
--COOM.sup.1, --OH and --NHR.sup.3 are preferable, and --COOM.sup.1 is
more preferable. One or more water-solubilizing groups may be contained in
R.sup.1 or R.sup.2.
Exemplary examples of the compound represented by formula (1) are shown
below, but the compound is not limited to these examples.
##STR1##
Compounds described above can be readily synthesized in accordance with the
method described in J. Pharm. Belg., 22(5-6) 213-219 (1967); U.S. Pat. No.
3,759,932; J. Org. Chem., Vol 23, 64-66 (1967); and J. med. Chem., Vol.10,
No.6, 1170-1172.
The compound represented by formula (2) is further described below. In the
formula (2), examples of the water-solubilizing group contained in R
include --SO.sub.3 M.sup.1, --COOM.sup.1, --OH and --NHR.sup.3, in which
M.sup.1 is a hydrogen atom, an alkali metal atom or a cation. R.sup.3
represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
--COR.sup.4, --COOR.sup.4 or --SO.sub.2 R.sup.4, in which R.sup.4
represents a hydrogen atom, an aliphatic group or an aromatic group. Of
these is preferred --COOM.sup.1. One or more water-solubilizing groups may
be contained in R.
The aliphatic hydrocarbon group, aromatic hydrocarbon group and
heterocyclic group represented by R are the same as defined in R.sup.1 and
R.sup.2 described above. R is preferably the aromatic hydrocarbon group of
a heterocyclic group.
The aliphatic group, aromatic group and hetocyclic group represented by R
may be substituted. The substituent is the same as defined in R.sup.1 and
R.sup.2. R can contain one or more of the substituents described above.
The substituents each may be further substituted. Specifically, it is
preferred that the substituent is substituted by an electron withdrawing
group.
In formula (2), S(M)y represents a group capable of being adsorbed to
silver halide. M represents a hydrogen atom, an alkali metal atom or a
cationic group, and preferably a hydrogen atom or an alkali metal; and y
represents 0 or an integer of 1 or more (and preferably 0 or 1), provided
that when y is 0, the formula represents R=S.
Exemplary examples of the compound represented by formula (2) are shown
below, but the compound is not limited to these examples.
##STR2##
The compound represented by formula (1) or (2) can be incorporayed into an
emulsion layer and/or a non-emulsion layer before, during or after
chemical sensitization. The amount to be incorporated is preferably 0.1 to
500 mg/m2, and more preferably 1 to 300 m.sup.2. The compound can be
incorporated by dissolving in a water-miscible organic solvent (e.g.,
methanol) or in the form of fine particles dispersed in a gelatin aqueous
solution. The compound can be present in the form of a silver compound in
the emulsion layer or the photographic material.
In cases where after completing crystal growth, a fine silver halide grain
emulsion is added, it is preferable to enhance solubility of silver halide
grains of substrate. Accordingly, it is preferred to employ a technique of
raising the temperature of an emulsion containing the silver halide grains
of substrate, vary the pAg or the pH, or add a silver halide solvent. When
the temperature is raised, it is preferably 3 to 30.degree. C., and more
preferably 7 to 20.degree. C. higher than that at the crystal step. The
pAg range, a preferred range of which depends of conditions including
halide composition and crystal habit, can be adjusted by adding a halide
aqueous solution or a silver salt aqueous solution. The pH can also be
adjusted with an appropriate acid or alkali. The silver halide solvent
includes known silver halide solvent such as ammonia, thioethers,
thioureas, thicyanates.
In the invention it is preferred to enhance uniformity among grains of
halide composition of the outermost surface of silver halide grains, in
the stage of chemical ripening. Various methods are applicable, including
a technique of adding to an emulsion containing silver halide grains of
substrate, a fine silver halide grain emulsion containing at least one of
fine silver iodide grains, fine silver bromide grains, fine silver
chloride grains, fine silver iodobromide grains, fine silver iodochloride
grains, fine silver chlorobromide grains and fine silver iodochlorobromide
grains; a technique of adding an aqueous solution containing at least one
of alkali iodide, alkali bromide and alkali chloride; and a technique of
using a halide ion releasing agent. Of these are preferred the addition of
a fine silver halide emulsion and the use of a halide ion releasing agent.
Herein the chemical ripening stage refers to the period of from the time
of completing physical ripening and desalting of a silver halide emulsion,
through addition of a chemical sensitizer, to the time of applying an
operation of stopping chemical ripening. The fine silver halide grain
emulsion or the halide ion releasing agent may be added separately at
intervals. After adding the fine grains or the releasing agent, another
chemically ripened emulsion may be added. The fine silver halide grain
size is preferably 0.15 .mu.m or less, more preferably 0.1 .mu.m or less,
and still more preferably 0.06 .mu.m or less. The fine silver halide grain
emulsion is added preferably at 30 to 80.degree. C., and more preferably
40 to 65.degree. C.
During the course of forming silver halide grains used in the invention,
silver nuclei can be formed. The silver nuclei can be formed by adding a
reducing agent to an emulsion or a mixing solution used for grain growth;
or by causing grains to grow or ripen at a low pAg of 7 or less or a high
pH of 7 or more. A combination these methods is a preferred embodiment of
the invention.
As a technique for forming silver nuclei, reduction sensitization has been
known, as described in J. Phot. Sci. 25, 19-27 pages (1977) and Phot. Sci.
Eng. 32, 113-117 pages (1979). As described by Michell and Lowe in Photo.
Korr. Vol 1, 20 (1957) and Phot. Sci. Eng. 19, 49-55 (1975), it has been
considered that silver nuclei formed through reduction sensitization
contribute sensitization through the following reaction on exposure:
Preferred reducing agents include thiourea dioxide, ascorbic acid and its
derivative, and a stannous salt. In addition, borane compounds, hydrazine
derivatives, formamidinesulfinic acid, silane compounds, amines or
polyamines, and sulfites are also appropriate reducing agents. The
reducing agent is added in an amount of 10.sup.-2 to 10.sup.-8 mol per mol
of silver halide.
To carry out ripening at a low pAg, there may be added a silver salt,
preferably aqueous soluble silver salt. As the aqueous silver salt is
preferably silver nitrate. The pAg in the ripening is 7 or less,
preferably 6 or less and more preferably 1 to 3 (herein, pAg=-log[Ag.sup.+
]).
Ripening at a high pH is conducted by adding an alkaline compound to a
silver halide emulsion or mixture solution for growing grains. As the
alkaline compound are usable sodium hydroxide, potassium hydroxide, sodium
carbonate, potassium carbonate and ammonia. In a method in which
ammoniacal silver nitrate is added for forming silver halide, an alkaline
compound other than ammonia is preferably employed because of lowering an
effect of ammonia.
The silver salt or alkaline compound may be added instantaneously or over a
period of a given time. In this case, it may be added at a constant rate
or accelerated rate. It may be added dividedly in a necessary amount. It
may be made present in a reaction vessel prior to the addition of
aqueous-soluble silver salt and/or aqueous-soluble halide, or it may be
added to an aqueous halide solution to be added. It may be added apart
from the aqueous-soluble silver salt and halide.
In the invention, an oxidizing agent may be used for the silver halide
emulsion. The following oxidizing agents can be used:
Hydrogen peroxide and its adduct (e.g., NaBO.sub.2 --H.sub.2 O.sub.2
--3H.sub.2 O, 2NaCO.sub.3 --3H.sub.2 O.sub.2, Na.sub.4 P.sub.2 O.sub.7
--2H.sub.2 O.sub.2, 2Na.sub.2 SO.sub.4 --H.sub.2 O.sub.2 --H.sub.2 O),
peroxy acid salt (e.g., K.sub.2 S.sub.2 o.sub.8, k.sub.2 C.sub.2 O.sub.6,
K.sub.4 P.sub.2 O.sub.8), K.sub.2 [Ti(O.sub.2)C.sub.2 O.sub.4 ]3H.sub.2 O.
In addition, peracetic acid, ozone, iodine, bromine and thiosulfonic acid
type compound are also usable.
The addition amount of the oxidizing agent depends on kind of a reducing
agent, conditions for forming silver nuclei, addition time and conditions
of the oxidizing agent, and is preferably 10.sup.-2 to 10.sup.-5 mol per
mol of silver halide.
The oxidizing agent may be added at any step during the course of preparing
silver halide emulsion The oxidizing agent may be added prior to addition
of the reducing agent. After adding the oxidizing agent, a reducing agent
may newly added to deactivate a oxidizing agent in excess. The reducing
agent, which is capable of oxidizing the above oxidizing agent, includes
sulfinic acids, di- or tri-hydroxybenzenes, chromanes, hydrazines or
hydrazides, p-phenylenediamines, aldehydes, aminophenols, ene-diols,
oximes, reducing sugars, phenidones, sulfites and ascorbic acid
derivatives. The reducing agent is added in an amount of 10.sup.-3 to
10.sup.3 mol per mol of silver halide.
Heavy metal ions usable in the invention are preferably Group VIII metal
elements of the periodic table, such as iron, iridium, platinum, paradium,
nickel, rhodium, osmium, ruthenium and cobalt; Group II metal elements,
such as cadmium, zinc and mercury; lead, molybdenum, tungsten, chromium.
Among these, transition metal ions, such as iron, iridium, platinum,
ruthenium and osmium are preferred. The heavy metal ion may be to a silver
halide emulsion in the form of a salt or a complex salt. In particular,
addition in the form of a complex salt is preferred, since it is easily
incorporated in the grain, resulting in larger effects. In cases where the
heavy metal ion forms a complex, examples of ligands include a cyanide,
thiocyanate, isothiocyanate, cyanate, chloride, bromide, iodide, carbonyl,
and ammonia. Among these, thiocyanate, isothiocyanate and cyanate are
preferred. The heavy metal ion may be contained in silver halide emulsion
grains by adding a heavy metal compound at a time before, during, or after
forming silver halide grains and during physical ripening. For example,
the heavy metal compound is added, in the form of a aqueous solution, at a
desired timing. It may be contained in silver halide, and the resulting
silver halide is continuously added over a period of forming silver halide
grains. The heavy metal is added in an amount of 1.times.10.sup.-9 to
1.times.10.sup.-2 and preferably, 1.times.10.sup.-8 to 1.times.10.sup.-3
mol per mol of silver halide.
The amount of a hydrophilic binder contained in a silver halide emulsion
layer is preferably 3.0 g/m.sup.2 or less, and more preferably 1.0 to 2.0
g/m.sup.2 or less, in cases where the emulsion layer is coated on both
sides of the support. In cases where coated on one side of the support, it
is 6.0 g/m.sup.2 or less,and more preferably 4.0 g/m.sup.2 or less.
The silver halide light sensitive photographic material according to the
invention includes a silver halide black-and-white photographic material
(e.g., a photographic material for medical use, photographic material for
use in graphic art, negative photographic camera material), a color
photographic material (e.g., a color negative photographic material, color
reversal photographic material, color photographic material for print, a
diffusion transfer photographic material and a heat-developable
photographic material. Of these is preferable the silver halide
black-and-white photographic material, and more preferably the
photographic material for medical use.
The silver halide emulsion layer or light-insensitive hydrophilic colloid
layer of the photographic material according to the invention preferably
contains an organic or inorganic hardener. Examples of the hardener
include chromates (e.g., chromium alum, chromium acetate), aldehydes
(e.g., formaldehyde, glyoxal, glutar aldehyde), N-methylol compounds
(e.g., dimethylol urea, methylol dimethylhydantoin), dioxane derivatives
(e.g., 2,3-dihydoxydioxane), active vinyl compounds {e.g.,
1,3,5-triacryloyl-hexahydro-s-triazine, bis(vinylsulfonyl)methyl ether,
N,N'-methlenebis[.beta.-(vinylsulfonyl)propioneamide]}, muco-halogenic
acids (e.g., mucochloric acid, mucophenoxychloric acid), isooxazoles, and
2-chloro-6-hydroxytriazinylated gelatin. These hardener can be employed
singly or in combination. The hardener is preferably added in the coating
stage of the photographic material, in an optimal amount so as to adjust
the swelling ratio in the process of developing, fixing and washing,
whereby the water content of the photographicmaterial prior to drying is
reduced andsuitability for rapid access is provided.
Support usable in the silver halide photographic material according to the
invention include those described in RD-17643 on page 28 and RD-308119 on
page 1009. An appropriate support is a plastic resin film. The surface of
the support may be provided with a sublayer, or subjected to corona
discharge or UV ray exposure to improve adhesive property of a coating
layer.
A variety of adjuvants may be incorporated to the photographic material in
accordance with its purpose. The adjuvants are described in Research
Disclosure (RD) 17643 (December., 1978), ibid 18716 (November., 1979), and
ibid 308119 (December., 1989). Kinds of compounds described in these RD
and described section are shown below.
______________________________________
RD-17643 RD-18716 RD-30
Additive Page Sec. Page Page Sec.
______________________________________
Chemical sensitizer
23 III 648 upper right
996 III
Sensitizing dye 23 IV 648-649 996-8 IVA
Desensitizing dye 23 IV 998 IVB
Dye 25-26 VIII 649-650 1003 VIII
Developing accelerator 29 XXI 648 upper right
Antifoggant/stabilizer 24 IV 649 upper right 1006-7 VI
Brightening agent 24 V 998 V
Hardening agent 26 X 651 left 1004-5 X
Surfactant 26-27 XI 650 right 1005-6 XI
Plasticizer 27 XII 650 right 1006 XII
Slipping agent 27 XII
Matting agent 28 XVI 650 right 1008-9 XVI
Binder 26 XXII 1003-4 IX
Support 28 XVII 1009 XVII
______________________________________
The photographic material of the invention is processed by use of
processing solutions described in RD-17643, XX-XXI, pages 29-30 and
RD-308119, XX-XI, pages 1011-1012.
Dihydroxybenzenes such as hydroquinone, 3-pyrazolidones such as
1-phenyl-3-pyrazolidone and aminophenols such as N-methyl-aminophenol are
used singly or in combination thereof, as a developing agent used in
black-and-white photography. A developing solution may optionally contain
a preserver, alkali agent, pH buffering agent, antifoggant, hardener,
development accelerating agent, surfactant, defoamer, toning agent,
water-softener, dissolving aid or thickener.
A fixing agent such as a thiosulfate or thiocyanate is used in a fixer.
Further, a water soluble aluminum salt such as aluminum sulfate or
potassium alum may be contained as a hardener. In addition, preserver,
pH-adjusting agent, water-softener may be contained.
In an automatic processor used in the invention which has mechanism of
supplying a solid processing composition to a processing bath, known
methods disclosed in Japanese Utility Model open to public inspection
(OPI) publication 63-137783, 63-97522 and 1-85732 are available as a
supplying means, in the case of the solid processing composition in a
tablet form. If at least function for supplying the tablet to a processing
bath is provided, any method may be usable. In the case of a solid
processing composition in the form of granules or powder, gravity drop
system described in Japanese Utility Model OPI publication 62-81964,
63-84151 and 1-292375, and screw-driving system described in Japanese
Utility Model OPI publication 63-105159 and 63-195345 are known methods,
but the present invention is not limited to these methods. The solid
processing composition may be dropped in any portion of a processing bath.
It is preferably the portion which is connected to a processing section
and in which a processing solution flows to the processing portion. It is
more preferably a structure in which a given amount of the processing
solution circulates between the connected portion and the processing
section and dissolved components are transferred to the processing
section. The solid processing composition is preferably dropped into a
temperature-controlled processing solution.
Dihydroxybenzenes described in JP-A 6-13859, aminophenols, pyrazolidones
and reductones are usable, as a developing agent, in a developer used in a
processing method relating to the present invention. Among the
pyrazolidones are preferred those substituted at the 4-position (Dimezone,
Dimezone-S), which are water soluble and superior in storage stability
when used in the form of the solid composition.
The developing solution used in the invention may contain, as a
preservative, an organic reducing agent as well as a sulfite described in
JP-A 6-138591. Compounds described in JP-A 5-289255 and 6-308680 (general
formulas 4-a and 4-b) may be contained as an antisludging agent. Addition
of a cyclodextrin compound is preferred, particularly as described in JP-A
1-124853.
An amine compound may be added to the developing solution, as described in
U.S. Pat. No. 4,269,929. A buffering agent may be used in the developing
solution, including sodium carbonate, potassium carbonate, potassium
bicarbonate, trisodium phosphate, tripotassium phosphate, dipotassium
phosphate, sodium borate, potassium borate, sodium tetraborate, potassium
tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium
o-hydroxybenzoate (potassium salicylate), sodium 5-sulfo-2-hydroxybenzoate
(sodium salicylate) and potassium 5-sulfo-2-hydroxybenzoate (potassium
salicylate).
Thioether compounds, p-phenylenediamine compounds, quaternary ammonium
salts, p-aminophenols, amine compounds, polyalkylene compounds;
1-phenyl-3-pyrazolidones; hydrazines, mesoion type compound and imidazoles
may be added as a development accelerating agent. Alkali metal halides
such as potassium iodide are used as a antifoggant. Organic antifoggants
include benzotriazole, 6-nitrobenzimidazole, 5-nitrobenzimidazole,
5-methylbenzotriazole, 5-nitrobenzotriazole, 5-chlorobenzotriazole,
2-thiazolyl-benzimidazole, 2-thiazolylmethyl-benzimidazole, indazole,
hydroxyazaindolizine, adenine and 1-pheny-5-mercaptotetrazole.
Further, methylcellosolve, methanol, acetone, dimethylformamide,
cyclodextrin compounds compounds described in Japanese Patent 47-33378 and
44-9509 can be optionally used as an organic solvent for enhancing the
solubility of a developing agent. Furthermore, a variety of additives,
such as an anti-staining agent, antisludging agent and interlayer
effect-promoting agent can be used.
A fixer usable in the invention includes compounds known as the fixer.
There can be added a fixing agent and a pH buffering agent, a hardener or
a preservative. Furthermore, a bisulfite adduct of a hardening agent or
known fixing accelerator can also be added.
Prior to processing, an addition of a starter is preferred. The starter is
added preferably in a solid form. As the starter are employed organic
acids such as polycarboxylic acid, alkali-earth metal halide such as KBr,
organic restrainer and developing accelerator.
There may be used an automatic processor in which a mechanism of providing
water or acidic rinsing solution between a developing bath and a fixing
bath or the fixing bath and a washing bath, as disclosed in JP-A 3-264953.
A device for preparing a developer or fixer may be built therein. The
photographic material may be processed with conventional processing
solutions without use of solid processing composition.
The photographic material according to the invention can be processed with
a developer and/or developer replenishing solution containing a compound
represented by formula (3).
The compound may be added to a developer in an amount of 0.005 to 0.5,
preferably 0.02 to 0.4 mol per liter of the developer. Next, the compound
represented by formula (1) will be explained more in detail.
In the formula, R.sup.1 and R.sup.2 each represent a hydroxy group, amino
group, acylamino group, alkylsulfonylamino group, arylsulfonylamino group,
alkoxycarbonylamino group, mercapto group and alkylthio group; Z
represents a group of atoms necessary for forming a 5 or 6-membered ring.
Concretely, R.sup.1 and R.sup.2 independently represent a hydroxy group,
amino group (which may be substituted by an alkyl group having 1 to 10
carbon atoms such as methyl, ethyl, n-butyl or hydroxyethyl), acylamino
group (i.e., acetyl amino, benzoylamino, etc.); alkylsulfonylamino group
(e.g., methanesulfonylamino); arylsulfonylamino group
(benzenesulfonylamino, p-toluenesulfonylamino, etc.); alkoxycarbonylamino
group (methoxycarbonylamino group etc.); mercapto group; alkylthio group
(methylthio, ethylthio etc.). As preferred examples of R.sup.1 and R.sup.2
are cited a hydroxy group, amino group, alkylsulfonylamino group and
arylsulfonylamino group. The ring is 5 or 6-membered one including two
vinyl carbon substituted by R.sup.1 and R.sup.2, and carbonyl carbon. Z is
a 5- or 6-membered ring, preferably comprised of a carbon atom, oxygen
atom or nitrogen atom. Thus, Z is comprised of a combination of --O--,
--C(R.sup.3)(R.sup.4)--, --C(R.sup.5)=, --C(.dbd.O)--, --N(R.sup.6)--, and
--N.dbd., in which R.sup.3, R.sup.4, R.sup.5 and R.sup.6 independently
represent a hydrogen atom, alkyl group having 1 to 10 carbon atoms (which
may be substituted by a hydroxy, carboxy or sulfo group), aryl group
having 6 to 15 carbon atoms (which may be substituted by an alkyl group,
halogen atom, hydroxy, carboxy or sulfo group), hydroxy group or carboxy
group. The 5- or 6-membered ring includes saturated or unsaturated
condensed ring. Examples of the 5- or 6-membered ring include a
dihydrofuranone ring, dihydropyrrone ring, pyranone ring, cyclopentenone
ring, cyclohexenone ring, pyrrolinone ring, pyrazolinone ring, pyridone
ring, azacyclohexenone ring, and uracil ring. Among these are preferred a
dihydrofuranone ring, cyclopentenone ring, cyclohexenone ring,
pyrazolinone ring, azacyclohexenone ring and uracil ring. Examples of the
compounds represented by formula (1) are shown as below, but the present
invention is not limited thereto.
##STR3##
A developing agent can be incorporated in a layer of the photographic
material, such as an emulsion layer, a protective layer, an interlayer or
other light-insensitive layers, and preferably the emulsion layer, the
interlayer which is farther from the support than the emulsion layer, and
the protective layer. The developing agent to be incorporated is 0.01 to
10 mol, preferably 0.05 to 2 mol, and more preferably 0.1 to 1 mol per mol
of silver halide of the emulsion layer.
The average particle size of a fluorescent substance of a fluorescent
intensifying screen (hereinafter, denoted as intensifying screen) employed
in the image forming process relating to the invention is preferably 7
.mu.m or less, and more preferably 4 .mu.m or less, in terms of reducing
diffusion of light in the fluorescent substance layer which deteriorates
sharpness. When the average particle size is too small, the sensitivity is
markedly reduced. Accordingly, the average particle size is preferably o.3
mm or more, and more preferably 0.5 .mu.m or more. Herein, the average
particle size is a number average.
The ratio by weight of a binder to the fluorescent substance of
intensifying screen used in the invention is 0.1 to 3.0% and
dispersibility of the fluorescent substance in the binder is enhanced, so
that the binder is uniformly present on the surface of the fluorescent
substance and the fluorescent substance particles are brought so close
together, leading to enhanced filling ratio. The ratio by weight of a
binder to the fluorescent substance of intensifying screen used in the
invention is 0.1 to 3.0%, the filling ratio is 68% or more and the layer
thickness is 135 to 200 .mu.m.
The fluorescent substance layer, in general, comprises fluorescent
substance particles and binder and voids. The void is a space in which the
fluorescent substance particles and binder is not substantially present.
Accordingly, as the binder decreases, the voluminal void proportion
increases. The void acts as a scattering factor of light, reducing
diffusion of emission from the fluorescent substance and enhancing
sharpness. When the weight ratio of the binder to the fluorescent
substance exceeds 3.0%, voids in the layer decrease, reducing diffusion of
emission and leading to deteriorated sharpness. When the weight ratio of
the binder to the fluorescent substance is less than 0.1%, on the other
hand, it becomes difficult for the binder to cover the overall surface of
the fluorescent substance, function of the binder of binding the
fluorescent substance together is hard to be displayed, and a high filling
ratio can be achieved. Further, it becomes hard for the binder to be
uniform over the whole layer, the fluorescent substance becoming hard to
be homogeneously present, resulting in non-uniform emission and
deteriorated image sharpness.
Preferred fluorescent substances used in the intensifying screen include
tungstate fluorescent substances (CaWO.sub.4, MgWO.sub.4, CaWO.sub.4 :Pb);
terbium-activated rare earth oxysulfide fluorescent substances [Y.sub.2
O.sub.2 S:Tb, Gd.sub.2 O.sub.2 S:Tb, La.sub.2 O.sub.2 S:Tb, (Y.Gd)2O.sub.2
S:Tb, (Y.Gd)O.sub.2 S:Tb.Tm3; terbium-activated rare earth phosphate
fluorescent substances (YPO.sub.4 :Tb, GdPO.sub.4 :Tb, LaPO.sub.4 :Tb);
terbium-activated rare earth oxyhalide fluorescent substances (LaOBr:Tb,
LaOBr:Tb, Tm, LaOCl: Tb, Tm, GdOBr:Tb, GdOCl) and thulium-activated rare
earth oxyhalide fluorescent substances (LaOBr:Tm, LaOCl:Tm); barium
sulfate fluorescent substances [BaSO.sub.4 Pb, BaSO.sub.4 :Eu.sup.2+,
(Ba.Sr)SO.sub.4 :Eu.sup.2+ ]; bivalent europium-activated alkali earth
metal phosphate fluorescent substances [Ba.sub.2 PO.sub.4).sub.2
:Eu.sup.2+, (Ba.sub.2 PO.sub.4).sub.2 :Eu.sup.2+ ]; bivalent
europium-activated alakli earth metal fluorohalide fluorescent substances
[BaFCl:Eu.sup.2+, BaFBr:Eu.sup.2+, BaFCl:Eu.sup.2+.Tb, BaF.sub.2. BaCl .
KCl:Eu.sup.2+ (Ba.Mg)F.sub.2. BaCl. KCl:Eu.sup.2+ ]; iodide fluorescent
substances [ZnS:Ag(Zn.Cd)S:Ag, (Zn.Cd)S:Cu, (Zn.Cd)S:Cu.Al]; hafnium
phosphate fluorescent substances (HfP.sub.2 O.sub.7 :Cu); tantalate
fluorescent substances (YTaO.sub.4, YTaO4:Tm, YTaO.sub.4 :Nb,
[Y,Sr]TaO.sub.4 :Nb, GdTaO.sub.4 :Tm, GD.sub.2 O.sub.3. Ta.sub.2 O.sub.5.
B.sub.2 O.sub.5 :Tb].
It is preferred to fill the fluorescent substance in sloped grain structure
to form the intensifying screen. Specifically, it is preferred that a
fluorescent substance with a large particle size is coated in the surface
protective layer-side and another fluorescent substance with smaller
particle size is coated in the support-side. The small particle size is in
the range of 0.5 to 2.0 .mu.m and larger one is 10 to 30 .mu.m.
As a binder, a thermoplastic elastomer whose softening temperature or a
melting point is 30 to 150.degree. C. is used singly or in combination
with other binder polymers. The thermoplastic elastomer has elasticity at
room temperature and has fluidity when heated. Therefore, it can prevent
damage of the fluorescent substance due to pressure in compression. As
examples of a thermo-plastic elastomer, polystyrene, polyolefin,
polyurethane, polyester, polyamide, polybutadiene, ethylene vinyl acetate
copolymer, poly vinyl chloride, natural rubbers, fluorine-containing
rubbers, polyisoprene, chlorinated polyethylene, styrene-butadiene rubbers
and silicone rubbers are cited. The component ratio of thermo-plastic
elastomer in the binder is allowed to be 10 wt % or more and 100 wt % or
less. However, it is desirable that the binder is composed of the
thermo-plastic elastomer as much as possible, especially is composed of a
thermo-plastic elastomer of 100 wt %.
For producing the above-mentioned radiographic intensifying screen, it is
preferable to produce it by a production method including
1) a step forming a fluorescent substance sheet composed of a binder and a
fluorescent substance
2) a step providing the above-mentioned fluorescent substance sheet on a
support and adhering the above-mentioned fluorescent substance sheet on
the support while compressing at a softening temperature or melting point
or more of the above-mentioned binder.
First of all, step 1) will be explained. The fluorescent substance sheet
which is a fluorescent substance layer of a radiographic intensifying
screen can be produced by coating a coating solution, wherein a
fluorescent substance is dispersed uniformly in a binder solution, on a
tentative support for forming the fluorescent substance sheet, drying and
peeling it off from the tentative support. Namely, first of all, a binder
and fluorescent substance particles are added to an appropriate organic
solvent and then, stirred to prepare a coating solution wherein the
fluorescent substance is dispersed uniformly in the binder solution.
As examples of a solvent for preparing a coating solution, lower alcohols
such as methanol, ethanol, n-propanol and n-butanol; chlorine-containing
hydrocarbons such as methylenechloride and ethylenechloride; ketones such
as acetone, methylethylketone and methylisobutylketone; esters of lower
fatty acids and lower alcohols such as methyl acetate, ethyl acetate and
butyl acetate; ethers such as dioxane, ethyleneglycolmonoethylether and
ethyleneglycolmonomethylether and their mixtures can be cited. The mixture
ratio between the binder and the fluorescent substance in the coating
solution varies depending upon the characteristic of the radiographic
intensifying screen and the kind of fluorescent substance. Generally, the
mixture ratio of the binder and the fluorescent substance is from 1:1 to
1:100 (by weight), and preferably from 1:8 to 1:40 (by weight).
Various additives such as a dispersant for improving dispersing property of
a fluorescent substance in aforesaid coating solution and a plasticizer
for improving binding force between a binder and a fluorescent substance
in the fluorescent substance layer after being formed may be mixed.
Examples of a dispersant used for the above-mentioned purpose include
phthalic acid, stearic acid, caprolic acid and lipophilic surfactants may
be cited. Examples of a plasticizer include phosphates such as triphenyl
phosphate, tricresyl phosphate and diphenyl phosphate; phthalates such as
diethyl phthalate and dimethoxyethyl phthalate; ester glycols such as
ethylphthalylethyl glycolate and butylphthalylbutyl glycolate; and
polyesters of polyethylene glycols and aliphatic dibasic acids such as
polyester of triethylene glycol and adipic acid and polyester between
diethylene glycol and succinic acid are cited. Next, the coating layer is
formed by coating the coating solution containing the fluorescent
substance and the binder prepared in the above-mentioned manner on the
tentative support for forming a sheet uniformly. This coating operation
can be conducted by the use of a conventional means such as a doctor blade
method, a roll coater method and a knife coater method.
A material of the tentative support can be selected from glass, metal plate
or conventional materials as a support for an intensifying screen of
X-ray. Examples of such materials include plastic films such as cellulose
acetate, polyester, polyethylene terephthalate, polyamide, polyimide,
triacetate and polycarbonate, metallic sheets such as aluminium foil and
aluminium alloy foil, an ordinary paper, baryta paper, resin-coated paper,
pigment paper containing a pigment such as titanium dioxide, paper wherein
polyvinyl alcohol is subjected to sizing, ceramic plates or sheets such as
alumina, zirconia, magnesia and titania. A coating solution for forming
the fluorescent substance layer is coated on the tentative support and
dried. Following this, the coating layer is peeled off from the tentative
support so that the fluorescent substance sheet which will be a
fluorescent substance layer of a radiographic intensifying screen is
formed. Therefore, it is desirable that a mold-releasing agent is coated
on the surface of the tentative support and that the fluorescent substance
sheet formed is easily peeled off from the tentative support.
Next, step 2) will be explained. First of all, a support for a fluorescent
substance sheet prepared in the above-mentioned manner is prepared. This
support can be selected arbitrarily from the same materials as those used
for a tentative support used in forming the fluorescent substance sheet.
In a conventional radiographic intensifying screen, in order to strengthen
binding between a support and a fluorescent substance layer and in order
to improve sensitivity or image quality (sharpness and graininess) as the
radiographic intensifying screen, it is known to coat a polymer substance
such as gelatin as an adhesive layer on the surface of a support on the
side of the fluorescent substance layer or to provide thereon a
light-reflection layer comprising a light-reflective substance such as
titanium dioxide or a light-absorption layer comprising a light-absorptive
substance such as carbon black. The support used in the present invention
may be provided with each of the above-mentioned layer. The constitution
may be arbitrarily selected depending upon the purpose and application of
the desired radiographic intensifying screen. The fluorescent substance
sheet obtained through step a) is loaded on a support. Next, the
fluorescent substance sheet is stuck on the support while compressing it
at a softening temperature or a melting point or higher of the binder.
In the above-mentioned manner, by the use of a method that compress the
fluorescent substance sheet without fixing it on the support in advance,
the sheet can be spread thinly. Accordingly, it prevents damage of the
fluorescent substance. In addition, compared to a case wherein the sheet
is fixed for being pressed, a higher fluorescent substance filling rate
can be obtained even with the same pressure. Examples of a compressor used
for compressing processing of the present invention include conventional
ones such as a calendar roll and a hot press. In compression processing by
the use of the calendar roll, the fluorescent substance sheet obtained
through step a) is loaded on the support, and then, the sheet is passed
through rollers heated to the softening temperature or the melting point
of the binder or higher at a certain speed. However, a compressor used for
the present invention is not limited thereto. Any compressing means can be
used, provided that it can compress the sheet while heating it. The
compression pressure is preferably 50 kg/cm.sup.2 or more.
In an ordinary radiographic intensifying screen, a transparent protective
layer is provided for protecting the fluorescent substance layer
physically and chemically on the surface of the fluorescent substance
layer opposite to that being in contact with the support, as described
before. Such a protective layer is preferably provided in the radiographic
intensifying screen of the present invention. Layer thickness of the
protective layer is ordinarily in a range from about 0.1 to 20 .mu.m. The
transparent protective layer can be formed by a method that coats a
solution prepared by dissolving a transparent polymer such as cellulose
derivatives including cellulose acetate and nitro cellulose; and a
synthetic polymer including polymethyl methacrylate, polyvinyl butylal,
polyvinyl formal, polycarbonate, polyvinyl acetate, vinyl chloride-vinyl
acetate copolymer on the surface of the fluorescent substance layer. In
addition, the transparent protective layer can also be formed by a method
that forms a sheet for forming a protective layer such as a plastic sheet
composed of polyethylene terephthalate, polyethylene naphthalate,
polyethylene, polyvinylidene chloride or polyamide; and a protective layer
forming sheet such as a transparent glass plate is formed separately and
they are stuck on the surface of the fluorescent substance layer by the
use of an appropriate adhesive agent.
As a protective layer used for the radiographic intensifying screen of the
present invention, a layer formed by a coating layer containing an organic
solvent soluble fluorescent resin is preferable. As a fluorescent resin, a
polymer of a fluorine-containing olefin (fluoro olefin) or a copolymer of
a fluorine-containing olefin is cited. A layer formed by a fluorine resin
coating layer may be cross-linked. When a protective layer composed of a
fluorine resin is provided, dirt exuded from a film in contacting with
other materials and an X-ray film is difficult to come into inside of the
protective layer. Therefore, it has an advantage that it is easy to remove
dirt by wiping. When an organic solvent soluble fluorescent resin is used
as a material for forming a protective layer, it can be formed easily by
coating a solution prepared by dissolving this resin in a suitable solvent
and drying it. Namely, the protective layer is formed by coating the
protective layer forming material coating solution containing the organic
solvent soluble fluorine resin on the surface of fluorescent layer
uniformly by the use of the doctor blade and by drying it. This formation
of a protective layer may be conducted concurrently with the formation of
the fluorescent substance layer by the use of multilayer coating.
The fluorine resin is a homopolymer or copolymer of a fluorine containing
olefin (fluoroolefin). Its examples include polytetrafluoroethylene,
polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride,
tetrafluoroethylene-hexafluoropropylene copolymer and fluoroolefin-vinyl
ether copolymer. Though fluorine resins are insoluble in an organic
solvent, copolymers of fluoroolefins as a copolymer component are soluble
in an organic solvent depending upon other constituting units (other than
fluoroolefin) of the copolymers. Therefore, the protective layer can be
formed easily by coating a solution wherein the aforesaid resin is
dissolved in a suitable solvent for preparing on the fluorescent substance
layer to be dried. Examples of the above-mentioned copolymers include
fluoroolefin-vinyl ether copolymer. In addition, polytetrafluoroethylene
and its denatured product are soluble in a suitable fluorine-containing
organic solvent such as a perfluoro solvent. Therefore, they can form a
protective layer in the same manner as in the copolymer containing the
above-mentioned fluoroolefin as a copolymer component.
To the protective layer, resins other than the fluorine resin may be
incorporated. A cross-linking agent, a hardener and an anti-yellowing
agent may be incorporated. However, in order to attain the above-mentioned
object sufficiently, the content of the fluorine resin in the protective
layer is suitably 30 wt % or more, preferably 50 wt % or more and more
preferably 70 wt % or more. Examples of resin incorporated in the
protective layer other than the fluorine resin include a polyurethane
resin, a polyacrylic resin, a cellulose derivative,
polymethylmethacrylate, a polyester resin and an epoxy resin.
The protective layer for the radiographic intensifying screen used in the
present invention may be formed by either of an oligomer containing a
polysiloxane skeleton or an oligomer containing a perfluoroalkyl group or
by both thereof. The oligomer containing the polysiloxane skeleton has,
for example, a dimethyl polysiloxane skeleton. It is preferable to have at
least one functional group (for example, a hydroxyl group). In addition,
the molecular weight (weight average) is preferably in a range from 500 to
100000, more preferably 1000 to 100000, especially more preferably 3000 to
10000. In addition, the oligomer containing the perfluoroalkyl group (for
example, a tetrafluoroethylene group) preferably contains at least one
functional group (for example, a hydroxyl group: --OH) in a molecule. Its
molecular weight (weight average) is 500 to 100000, more preferably 1000
to 100000 and especially preferably 10000 to 100000. When an oligomer
containing a functional group is used, cross-linking reaction occurs
between the oligomer and a resin for forming a protective layer in forming
the protective layer so that the oligomer is taken into a molecule
structure of the layer-forming resin. Therefore, even when the X-ray
conversion panel is used for a long time repeatedly or cleaning operation
of the surface of the protective layer is carried out, the oligomer is not
taken off from the protective layer. Therefore, the addition of the
oligomer becomes effective for a long time so that use of the oligomer
having a functional group becomes advantageous. The oligomer is contained
in the protective layer preferably in an amount of 0.01 to 10 wt % and
especially 0.1 to 2 wt %.
In the protective layer, perfluoro olefin resin powder or silicone resin
powder may be added. As the perfluoro olefin resin powder or the silicone
resin powder, those having an average particle size of preferably 0.1 to
10 .mu.m, and more preferably 0.3 to 5 .mu.m. The above-mentioned
perfluoro olefin resin powder or the silicone resin powder is added to the
protective layer preferably in an amount of 0.5 to 30 wt % and more
preferably 2 to 20 wt % and especially preferably 5 to 15 wt%.
The protective layer of the intensifying screen is preferably a transparent
synthetic resin layer coated on the fluorescent substance layer and having
a thickness of 5 .mu.m or less. The use of a thick protective layer leads
to shorten the distance between the intensifying screen and a silver
halide emulsion and therefore enhance sharpness of the resulting X-ray
photographic image.
The intensifying screen used in the present invention is prepared in
accordance with the method described in JP-A 6-75097. The fluorescent
substance is coated by the multi-layer coating method so that larger
particles are arranged near the surface protective layer.
EXAMPLES
Embodiments of the present invention will be further explained based on
examples, but the present invention are by no means limited to these
examples.
Example 1
Preparation of Emulsion
To a vessel containing water of 1 liter of water, potassium bromide of 6 g
and gelatin of 7 g and maintained at 55.degree. C. were with stirring by
the double jet method for 37 sec. an aqueous silver nitrate solution of 37
cc (silver nitrate of 4 g) and an aqueous potassium bromide solution of 38
cc (potassium bromide of 5.9 g). Then, gelatin of 18.6 g was added with
raising the temperature to 70.degree. C. and thereafter, the pBr was
adjusted to 2.3 with a silver nitrate aqueous solution. A 25% aqueous
ammonia solution of 7 cc was added thereto and after physical-ripening for
10 min., a 100% acetic solution of 6.5 cc was added. Subsequently, an
aqueous solution of 18 g silver nitrate and an aqueous solution of
potassium bromide were added with maintaining the pBr by the controlled
double jet method in 35 min. When the grain growth reached a portion as
shown in Table 1 with respect to the final grains, fine silver iodide
grains were added. Herein, the final grains means those at the time when
the grain growth is completed. In Emulsion 6 in Table 1, for example, fine
silver iodide grains were added at the time when silver halide grains were
grown to 95%, in size, of the final grain. After allowing grains to grow
to the intended grain size, physical ripening continued further for 5 min.
at the same temperature and the emulsion was washed by the coagulation
process to remove soluble salts. The emulsion was raised to a temperature
of 40.degree. C., 30 g gelatin and 2.4 g pheoxyethanol were added thereto,
the ph was adjusted to 5.90 with sodium hydroxide and the pAg was adjusted
to 8.21 with an aqueoussilver nitrate solution or an aqueous potassium
bromide solution. Characteristics of silver halide grains of emulsions
Em-1 to 16 are shown in Table 1. In the Table, the iodide content of the
outermost layer of the grain were measure by the TOF-SIMs method
afore-described.
The resulting emulsion was chemically sensitized with stirring while
maintained at 56.degree. C. Thus, A sensitizing dye (A) of 460 mg/Ag mol
was added in the form of a solid particle dispersion, prepared as
described below; then, chemical ripening was optimally conducted by adding
ammonium thicyanate of 7.0.times.10.sup.-4 mol/Ag mol, potassium
chloroaurate, sodium thiosulfate, triphenylphosphine selenide of
3.0.times.10.sup.-6 mol/Ag mol and a compound as shown in Table 1; a fine
silver iodide grain emulsion of 3.times.10-3 mol/Ag mol was added; and
4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene (TAI) of 3.times.10.sup.-2
mol/Ag mol was added to stabilize the emulsion. Thus prepared emulsion No.
1 was shown in Table 1 with respect to its characteristics including the
grain for, the surface halide composition and its distribution among
grains. Similarly, emulsions No. 2 to 16 were prepared .Yen., as shown in
Table 1.
Preparation of Solid Particle Dispersion of Sensitizing Dye
Sensitizing dyes (A) and (B) were added in a ratio of 100:1 to water
maintained at 27.degree. C. and stirred by a high-speed dissolver at 3,500
rpm for a period of 30 to 120 min. to obtain a solid particle dispersion
of the sensitizing dyes. In this case, the dispersion was so adjusted that
the concentration of Dye (A) was 2%.
Sensitizing Dye (A):
5,5'-Dichloro-9-ethyl-3,3'-di-(3-sulfopropyl)oxacarbocyanine anhydride
Sensitizing Dye (B):
5,5'-Di-(butoxycarbonyl)-1,1'-diethyl-3,3'-di-(4-sulfobutyl)benzimidazoloc
arbocyanine
Preparation of Fine Silver Iodide Grains
______________________________________
A1
Ossein gelatin 100 g
KI 8.5 g
Distilled water to make 2,000 ml
B1
AgNO3 360 g
Distilled water to make 605 ml
C1
KI 352 g
Distilled water to make 605 ml
______________________________________
To a reaction vessel was added solution A1, and solutions B1 and C1 were
added by the double jet method at a constant flow rate for 30 min., while
the pAg was maintained at 13.5. The resulting silver iodide emulsion
(denoted as fine silver iodide grain emulsion) was a mixture of .beta.-AgI
and .gamma.-AgI with an average grain size of 0.06 .mu.m.
TABLE 1
__________________________________________________________________________
Surface
Av. halide
Emul- AgI Fine grain dia- Av. Projected content S-compound
sion Add. time
Amount meter.sup.a
V.C..sup.b
aspect
area.sup.c
AgI V.C..sup.d
Amount
No. (%) (mol/Ag mol) (.mu.m) (%) ratio (%) (mol %) (%) Compd. (mol/Ag
mol) Remark
__________________________________________________________________________
1 -- -- 0.90 21 4.5 98 -- -- -- -- Comp.
2 -- -- 0.90 21 4.5 98 -- -- 1-15 1.5 .times. 10.sup.-3 Comp.
3 100 0.4 0.90 21 4.5 98 2.8 25 -- -- Comp.
4 100 0.4 0.90 21 4.5 98 2.8 25 1-15 1.5 .times. 10.sup.-3 Comp.
5 100 0.4 0.90
21 4.5 98 2.8
25 2-10 1.5
.times.
10.sup.-3 Comp.
6 95 0.4 0.90 21 4.5 98 2.5 12 -- -- Comp.
7 95 0.4 0.90 21 4.5 98 2.5 12 1-15 1.5 .times. 10.sup.-3 Inv.
8 95 0.4 0.90 21 4.5 98 2.5 12 2-10 1.5 .times. 10.sup.-3 Inv.
9 70 0.4 0.90 21 4.5 98 1.5 12 -- -- Comp.
10 70 0.4 0.90 21 4.5 98 1.5 12 1-15 1.5 .times. 10.sup.-3 Inv.
11 70 0.4
0.90 21 4.5 98
1.5 12 1-15 1.5
.times.
10.sup.-2 Inv.
12 70 0.4
0.90 21 4.5 98
1.5 12 2-10 1.5
.times.
10.sup.-3 Inv.
13 100 0.7
0.90 21 4.5 98
3.4 25 1-15 1.5
.times.
10.sup.-3 Comp.
14 95 0.7 0.90 21 4.5 98 2.7 14 -- -- Comp.
15 95 0.7 0.90 21 4.5 98 2.7 14 1-15 1.5 .times. 10.sup.-3 Inv.
16 95 0.7
0.90 21 4.5 98
2.7 14 2-10 1.5
.times.
10.sup.-3
__________________________________________________________________________
Inv.
a: Equivalent circle diameter
b: Variation coefficient of grain diameter
c: Percentage of the projected area accounted for by tabular grains havin
an aspect ratio of 3 to 15
d: Variation coefficient of distribution among grains
Preparation of Coating Sample
Synthesis of Colloidal Tin Oxide Dispersion:
Stannic chloride hydrate of 65 g was dissolved in a 2000 cc aqueous
solution to obtain a solution. Subsequently, the solution was boiled to
obtain co-precipitates. The resulting precipitates were washed several
times with distilled water by decantation. After confirming no reaction
with chloride ions by adding dropwise silver nitrate to the distilled
water used for washing, the precipitate was added to water of 1000 cc and
dispersed, than, the total amount was made to 2000 cc. Further, 40 cc of
aqueous ammonia was added thereto and the mixture solution was heated to
obtain a colloidal gel dispersion. The sol dispersion was concentrated to
8% concentrate with blowing ammonia Thus prepared tin oxide sol was proved
to have a specific volume resistance of 3.4.times.10.sup.4 .OMEGA.cm.
Preparation of Subbed Support:
On both sides of a blue-tinted polyethylen terephthalate film base for use
in a X-ray film with a density of 0.170 and a thickness of 175 .mu.m,
which were subjected to corona discharge treatment at 0.5
kV.multidot.A.multidot.min./m.sup.2, a latex solution for subcoat (L-2),
as described below was coated so as to have a dry thickness of 0.2 .mu.m
and then L-1 as below was coated so as to have a dry thickness of 0.053
.mu.m, and dried at 123.degree. C. for 2 min.
(L-1)
##STR4##
m;n=1:1 (molar ratio) X: COOH or COONa
Y: COONa or COOCH.sub.2 CF.sub.2 CF.sub.2 H
(COONa:COOCH.sub.2 CF.sub.2 CF.sub.2 H=9:1 molar ratio)
Solid component 6% aqueous solution
(L-2):
A latex solution (solid component, 30%) of a copolymer comprised of
n-butylacrylate (10 wt. %), t-butylacrylate (35 wt. %), styrene (27 wt. %)
and 2-hydroxyethylacrylate (28 wt. %).
On one side of the film base was provided the same sublayer as Support 1
and on the other side, a mixture of tin oxide (SnO.sub.2) sol prepared in
Synthesis Example 1, afore-described L-2 and L-1 in a ratio by volume of
35:15:50 was coated so as to have a dry thickness of 0.12 .mu.m and a
coating amount of the sol component of 250 mg/M.sup.2, and further thereon
a mixture of L-1 and L-3 in a ratio by volume of 70:30 was coated so as to
have a dry thickness of 0.053 .mu.m, being dried at 120.degree. C. for 1
min. The base film was previously subjected to corona discharge treatment
at 0.5 kV. A. min./m.sup.2. The thus prepared support was referred to as
Support 2.
(L-3):
A mixture of 34.02 weight parts of dimethyl terephthalate, 25.52 weight
parts of dimethyl isophthalate, 12.97 weight parts of dimethyl
5-sulfoisophthalate sodium salt, 47.85 weight parts of ethylene glycol,
18.95 weight parts of 1,4-cyclohexanedimethanol, 0.065 weight parts of
calcium acetate monohydrate and 0.022 weight parts of manganese acetate
was subjected to ester exchange reaction at 170 to 220.degree. C. under
nitrogen gas, while methanol was distilled away. Thereafter, 0.04 weight
parts of trimethyl phosphate, 0.04 weight parts of antimonyl trioxide as a
polycondensation catalyst and 15.08 weight parts of
1,4-dicyclohexane-dicarboxylic acid were added, and a theoretical amount
of water was almost distilled away at a reaction temperature of 220 to
235.degree. C. to complete esterification. Further, the reaction system
was evacuated with heating by taking one hour and polycondensation was
carried out at 280.degree. C. and 1 mm Hg or less over a period of one
hour to obtain polyester product (intrinsic viscosity of 0.35).
To 7300 g of an aqueous solution of the thus prepared polyester polymer, 30
g of styrene, 30 g of butyl methaacrylate, 20 g of glycidyl methaacrylate,
20 g of acrylamide and 1.0 g of ammonium persulfate were added to be
reacted at 80.degree. C. over a period of 5 hr. The reaction product was
cooled down to a room temperature and adjusted so as to have a solid
component of 10 wt. %. A coating solution was thus-prepared.
(L-4):
A latex solution of a copolymer comprised of n-butylacrylate (40 wt. %),
styrene (20 wt. %) and glycidyl methaacrylate (40 wt. %).
Further to the subbed support, a complex latex, which was added to mulsion
and protective layers, was prepared as follows.
Synthesis of Complex Latex
To a 1,000 ml four-necked flask provided with a stirrer, a thermometer, a
dropping funnel, nitrogen introducing tube and reflax condenser were added
with introducing nitrogen gas to deoxigenate 360 cc of distilled water and
126 g of a 30 wt. % colloidal silica dispersion, and the mixture was
heated until reached the internal temperature of 80.degree. C. The
following surfactant of 1.3 g and ammonium persulfate as an initiator of
0.023 g were added, then vinyl pivalic acid of 12.6 g was added and the
reaction was continued for 4 hrs. Thereafter, the pH was adjusted to 6
with a cooled aqueous sodium hydroxide solution to obtain a complex latex.
Lx-1.
##STR5##
The above latex was comprised of an inorganic compound and hydrophobic
latex in a ratio of 4:1.
Preparation of Photographic Material
On both sides of subbed Support, coating solutions of a cross-over light
shielding layer, emulsion layer and protective layer were simultaneously
coated so as to have the following amount, and dried.
__________________________________________________________________________
First layer (Cross-over light shielding layer)
Gelatin 0.2 g/.sup.2
Solid particle dispersion of dye (AH) 20 mg/m.sup.2
Sodium dodecylbenzenesulfonate 5 mg/m.sup.2
Compound (I) 5 mg/m.sup.2
2,4-Dichloro-6-hydroxy-1,3,5-triazine 5 mg/m.sup.2
sodium salt
Colloidal silica (av.size 0.014 .mu.m) 10 mg/m.sup.2
Second layer (Emulsion layer)
The following additives were added to the emulsion
above-described.
Gelatin (including that of Emulsion) 1.2 mg/m.sup.2
Compound (G) 0.5 mg/m.sup.2
2,6-Bis(hydroxyamino)-4-diethylamino- 5 mg/m.sup.2
1,3,5-triazine
t-Butyl-catechol 5 mg/m.sup.2
Polyvinyl pyrrolidone (M.W. 10,000) 20 mg/m.sup.2
Styrene-anhydrous maleic acid copolymer 80 mg/m.sup.2
Sodium polystyrenesulfonate 80 mg/m.sup.2
Trimethylolpropne 350 mg/m.sup.2
Diethylene glycol 50 mg/m.sup.2
Nitrophenyl-triphenyl-phosphonium chloride 1 mg/m.sup.2
Ammonium 1,3-dihydroxybenzene-4-sulfonate 50 mg/m.sup.2
Sodium 2-mercaptobenzimidazole-5-sulfonate 5 mg/m.sup.2
Compound (H) 0.5 mg/m.sup.2
n-C.sub.4 H.sub.9 OCH.sub.2 CH(OH)CH.sub.2 N(CH.sub.2 COOH).sub.2 20
mg/m.sup.2
Compound (M) 5 mg/m.sup.2
Compound (N) 5 mg/m.sup.2
Colloidal silica 0.5 mg/m.sup.2
Compound (P) 0.2 mg/m.sup.2
Compound (Q) 0.2 mg/m.sup.2
Hydrophobic latex Lx-1 1.2 g/m.sup.2
Latex content 0.3 g/m.sup.2)
Water soluble Polymer 0.3 g/m.sup.2
(dextran with molecular weight of 50,000)
Leuco dye (R) 2 .times. 10.sup.-3 mol/Ag mol
Third layer (Lower protective layer)
Gelatin 0.3 g/m.sup.2
Dioctyl phthalate 0.2 g/m.sup.2
Forth layer (Upper protective layer)
Gelatin 0.3 g/m.sup.2
Matting agent of polymethyl methaacrylate 27 mg/m.sup.2
(area-averaged particle size 7.0 .mu.m)
Formaldehyde 20 mg/m.sup.2
2,4-Dichloro-6-hydroxy-1,3,5-triazine 10 mg/m.sup.2
sodium salt
Polysiloxan (SI) 50 mg/m.sup.2
Compound (I) 30 mg/m.sup.2
Compound (S-1) 7 mg/m.sup.2
Compound (K) 15 mg/m.sup.2
Compound (B) 2 mg/m.sup.2
Compound (J) 2 mg/m.sup.2
Compound (O) 50 mg/m.sup.2
Compound (S-2) 5 mg/m.sup.2
__________________________________________________________________________
The coating described above is per one size of the support. and the coating
amount was adjusted so as to have the silver coating amount of 1.5 g per
m.sup.2 of one side pf the support. Using emulsions No. 1 through 16,
Samples 1 to 16 were prepared. Chemical structure of the compounds
contained in he first layer (cross-over light shielding layer), second
layer (emulsion layer) and fourth layer (upper protective layer) is shown
below.
##STR6##
Preparation of Radiographic Intensifying Screen 1
Fluorescent substance Gd.sub.2 O.sub.2 S:Tb (average particle size, 1.8
.mu.m) 200 g
Polyurethane type thermoplastic elastomer
Deluxe TPKL-5-2625, solid component of 40% (product by Sumitomo Bayer
Corp.) 20 g
Nitrocellulose (nitration degree of 11.5%) 2 g
To the above was added methylethylketone as a solvent and the mixture was
dispersed with a propeller type mixer to obtain a coating solution for
fluorescent substance forming layer with a viscosity of 25 ps at
25.degree. C. (Binder/Fluorescent substance=1/22).
Separately, 90 g of soft type acryl resin, 50 g of nitrocellulose were
added to methylethylketone to be dispersed to obtain a dispersion with a
viscosity of 3 to 6 ps at 25.degree. C., as a coating solution to form a
sublayer.
A polyethylene terephthalate base (support) compounded with titanium
dioxide and with a thickness of 250 .mu.m was horizontally placed on a
glass plate and thereon was uniformly coated the coating solution of the
sublayer above-described by using a doctor blade. Thereafter, the coated
layer was dried with slowly increasing a temperature from 25 to
100.degree. C. to form the sublayer on the support. A thickness of the
sublayer was 15 .mu.m.
Further thereon was coated the coating solution of the fluorescent
substance in a thickness of 240 .mu.m by using a doctor blade and dried,
and subjected to compression. The compression was conducted by means of a
calendar roll at a pressure of 800 kgw/cm.sup.2 and a temperature of
80.degree. C. After compression, a transparent protective layer was formed
in accordance with the method described in Example 1 of JP-A 6-75097.
There was thus prepared radiographic intensifying screen 1 comprising a
support, sublayer, fluorescent substance layer and transparent protective
layer.
Preparation of Radiographic Intensifying Screen 2
A radiographic intensifying screen 2 comprising a support, sublayer,
fluorescent substance layer and transparent protective layer in the same
manner as the intensifying screen 1, except that a coating solution of the
fluorescent substance layer was coated in a thickness of 150 .mu.m and the
compression was not conducted.
Measurement of Characteristics of the Intensifying Screen
(1) Sensitivity measurement:
A one-sided photographic material MRE, product by Eastman Kodak in contact
with an objective intensifying screen was exposed to X-ray through a step
wedge having a width of log E=0.15, with varying exposure by distance.
Exposed photographic material were processed according to the method which
will be described in measurement of characteristics of the photographic
material.
Densitometry of the processed samples were made with visible light to
obtain a characteristic curve. A sensitivity is expressed as a relative
value of a reciprocal of X-ray exposure necessary for obtaining a density
of Dmin plus 1.0, based on the sensitivity at the time when using
intensifying screen 1 being 100 (standard value)
(source) Measurement of X-ray Absorbed Amount
The X-ray which is produced from a tungsten target tube at 80 kVp by three
phase power supply is allowed to transmit through an aluminum plate with a
thickness of 3 mm and reach an intensifying screen fixed at the position
of 200 cm farther from the tungsten anode of the target tube.
Subsequently, the amount of X-ray which is transmitted through the
intensifying screen is measure at the position of 50 cm behind the screen
by a ionization dosimeter.
The X-ray absorbed amount of each intensifying screen is shown in Table 2.
TABLE 2
______________________________________
X-ray absorbed
Phosphor Phosphor layer
Screen amount filling ratio thickness Sensi-
No. (%) (%) (.mu.m) tivity
______________________________________
1 55 72 154 100
2 37 65 105 61
______________________________________
Processing-1: Processing by the Use of a Solid Processing Composition
Containing Hydroquinone
Solid processing compositions for use in replenishing developer were
prepared according to the following operations (A) and (B).
Operation (A)
3000 g of hydroquinone, as a developing agent was ground into grain until
an average grain size became 10 .mu.m using a commercially available
bandom mill. 3000 g of sodium sulfite, 200 g of potassium sulfite and 1000
g of Dimezone were added to this powder and mixed by the mill for 30 min.
After granulating the mixture by adding 30 ml of water at room temperature
for 10 min., the granulated product was dried for 2 hr. using a fluidized
bed dryer at 40.degree. C. to remove moisture contained almost completely.
The thus prepared granules was mixed with 100 g of polyethylene glycol
6000 using a mixer for 10 min. in a room conditioned at 25.degree. C. and
40% R.H. Thereafter, the mixture was subjected to compression-molding on a
modified tabletting machine, Tough Press Collect 1527 HU, produced by
Kikusui Manufacturing Co., Ltd. to prepare 2500 tablets (A) having a
weight of 3.84 g per tablet, for use as developer-replenisher.
Operation (B)
100 g of DTPA, 4000 g of potassium carbonate, 10 g of
5-methylbenzotriazole, 7 g of 1-phenyl-5-mercaptotetrazole, 5 g of
2-mercaptohypoxanthine, 200 g of KOH and N-acetyl-D,L-penicillamine were
ground to form granules in a similar manner to the operation (A). After
granulation, the granules were dried at 50.degree. C. for 30 min. to
almost completely remove moisture contained. Thereafter, the mixture was
subjected to compression-molding on a modified tabletting machine, Tough
Press Collect 1527 HU, produced by Kikusui Manufacturing Co., Ltd. to
prepare 2500 tablets (B) having a weight of 1.73 g per tablet, for use as
developer-replenisher.
Tablets for use in fixer-replenishment were prepared according to the
following operations.
Operation (C)
14000 g of a mixture of ammonium thiosulfate/sodium thiosulfate (70/30 by
weight) and 1500 g of sodium sulfite were ground and mixed using
commercially available mixing machine. Adding water of 500 ml, the mixture
was granulated in a similar manner to the operation (A). After
granulation, the granules were dried at 60.degree. C. for 30 min. to
almost completely remove moisture contained. Thereafter, 4 g of
N-lauroylalanine was added thereto and the mixture was subjected to
compression-molding on a modified tabletting machine, Tough Press Collect
1527 HU, produced by Kikusui Manufacturing Co., Ltd. to prepare 2500
tablets (A) having a weight of 6.202 g per tablet, for use as
fixed-replenisher.
Operation (D)
1000 g of boric acid, 1500 g of aluminum sulfate 18 hydrate, 3000 g of
sodium hydrogen acetate (equimolar mixture of glacial acetic acid and
sodium acetate) and 200 g of tartaric acid were ground and mixed in a
similar manner to the above operation (A). Adding water of 100 ml, the
mixture was granulated in a similar manner to the operation (A). After
granulation, the granules were dried at 50.degree. C. for 30 min. to
almost completely remove moisture contained. Thereafter, 4 g of
N-lauroylalanine was added thereto and the mixture was subjected to
compression-molding on a modified tabletting machine, Tough Press Collect
1527 HU, produced by Kikusui Manufacturing Co., Ltd. to prepare 1250
tablets (B) having a weight of 4.562 g per tablet, for use as
fixed-replenisher.
______________________________________
Starter:
______________________________________
Glacial acetic acid 2.98 g
KBr 4.0 g
Water to make 1 liter
______________________________________
At the start of processing, tablets for developer were dissolved in water
to prepare a developer and 330 ml of the starter was added to 16.5 l of
the developer to prepare a starting developer solution. The start solution
was introduced in a developer bath and processing was started. The pH of
the developer solution was 10.45.
Photographic materials prepared in Example 1 were exposed so as to give a
density of 1.0 and subjected to running-processing. Processing was carried
out using an automatic processor, SRX-502, which was provided with a input
member of a solid processing composition and modified so as to complete
processing in 15 sec. During running-processing, to the developer solution
were added tablets (A) and (B), each 2 tablets and 76 ml of water per 0.62
m.sup.2 of the photographic material. When each of the tablets (A) and (B)
was dissolved in water of 38 ml, the pH was 10.70. To the fixer solution
were added 2 tablets of (C) and 1 tablet of (D) per 0.62 m.sup.2 with 74
ml of water. Addition of water was started at the same time of that of the
tablets and continued at a constant rate further for 10 min. in proportion
to a dissolving rate of the solid processing composition.
______________________________________
Processing condition:
______________________________________
Developing time: 4 sec.
Fixing time: 3.1 sec.
Washing time: 2 sec.
between washing and drying (squeegee): 1.6 sec.
Drying time: 4.3 sec.
Total processing time: 15 sec.
______________________________________
Processing-2: Processing by the Use of a Solid Processing Composition not
Containing Hydroquinone
Solid processing compositions for use in replenishing developer were
prepared according to the following operations (E) and (F).
Operation (E)
13000 g of sodium erythorbic acid, as a developing agent was ground into
grain until an average grain size became 10 .mu.m using a commercially
available bandom mill. 4877 g of sodium sulfite, 975 g of phenidone and
1635 g of DTPA were added to this powder and mixed by the mill for 30 min.
After granulating the mixture by adding 30 ml of water at room temperature
for 10 min., the granulated product was dried for 2 hr. using a fluidized
bed dryer at 40.degree. C. to remove moisture contained almost completely.
The thus prepared granules was mixed with 2167 g of polyethylene glycol
6000 using a mixer for 10 min. in a room conditioned at 25.degree. C. and
40% R.H. Thereafter, the mixture was subjected to compression-molding on a
modified tabletting machine, Tough Press Collect 1527 HU, produced by
Kikusui Manufacturing Co., Ltd. to prepare 2500 tablets (A) having a
weight of 8.715 g per tablet, for use as developer-replenisher.
Operation (F)
19500 g of potassium carbonate, 8.15 g of 1-phenyl-5-mercaptotetrazole 3.25
g of sodium hydrogen carbonate, 650 g of glutar aldehyde sulfite adduct
and 1354 g of polyethylene glycol 6000 were ground to form granules in a
similar manner to the operation (E). After granulation, the granules were
dried at 50.degree. C. for 30 min. to almost completely remove moisture
contained. Thereafter, the mixture was subjected to compression-molding on
a modified tabletting machine, Tough Press Collect 1527 HU, produced by
Kikusui Manufacturing Co., Ltd. to prepare 2500 tablets (F) having a
weight of 9.90 g per tablet, for use as developer-replenisher.
Tablets for fixer were prepared according to the following operations.
Operation (G)
18560 g of a mixture of ammonium thiosulfate, 1392 g of sodium thiosulfate,
580 g of sodium hydroxide and 2.32 g of disodium
ethylenediaminetetraacetate were ground and mixed using commercially
available mixing machine. Adding water of 500 ml, the mixture was
granulated in a similar manner to the operation (A). After granulation,
the granules were dried at 60.degree. C. for 30 min. to almost completely
remove moisture contained. The resulting granules were subjected to
compression-molding on a modified tabletting machine, Tough Press Collect
1527 HU, produced by Kikusui Manufacturing Co., Ltd. to prepare 2500
tablets (G) having a weight of 8.214 g per tablet, for use as
fixed-replenisher.
Operation (H)
1860 g of boric acid, 6500 g of aluminum sulfate 18 hydrate, 1860 g of
glacial acetic acid and 928 g of sulfuric acid (50 wt %) were ground and
mixed in a similar manner to the above operation (A). Adding water of 100
ml, the mixture was granulated in a similar manner to the operation (A).
After granulation, the granules were dried at 50.degree. C. for 30 min. to
almost completely remove moisture contained. The resulting granulates were
subjected to compression-molding on a modified tabletting machine, Tough
Press Collect 1527 HU, produced by Kikusui Manufacturing Co., Ltd. to
prepare 1250 tablets (H) having a weight of 4.459 g per tablet, for use as
fixed-replenisher.
______________________________________
Starter:
______________________________________
Glacial acetic acid 210 g
KBr 350 g
Water to make 1 liter
______________________________________
At the start of processing, tablets for developer were dissolved in water
to prepare a developer and 330 ml of the starter was added to 16.5 1 of
the developer to prepare a starting developer solution. The start solution
was introduced in a developer bath and processing was started. The pH of
the developer solution was 10.45.
Photographic materials prepared in Example 1 were exposed so as to give a
density of 1.0 and subjected to running-processing. Processing was carried
out using an automatic processor, SRX-502, which was provided with a input
member of a solid processing composition and modified so as to complete
processing in 15 sec. During running-processing, to the developer solution
were added one tablets of (E), two tablets of (F) and 20 ml of water per
0.62 m.sup.2 of the photographic material. When each of the tablets (A)
and (B) was dissolved in water of 20 ml, the pH was 10.70. To the fixer
solution were added 4 tablets of (G) and 2 tablet of (H) per 1.00 m.sup.2
with 50 ml of water. Addition of water was started at the same time of
that of the tablets and continued at a constant rate further for 10 min.
in proportion to a dissolving rate of the solid processing composition.
______________________________________
Processing condition:
______________________________________
Developing time: 4 sec.
Fixing time: 3.1 sec.
Washing time: 2 sec.
between washing and drying (sgueegee): 1.6 sec.
Drying time: 4.3 sec.
Total processing time: 15 sec.
______________________________________
Processing-3: Processing by the Use of a Solid Processing Composition not
Containing Hydroquinone and Containing a Compound Represented by Formula
(3)
Solid processing compositions for use in replenishing developer were
prepared in a manner similar to Processing-2, except that sodium
erythorbate used in processing-2 was replaced by an eqimolar amount of
exemplified Compound 3-1 of formula (3).
Sensitometry Evaluation:
Photographic material samples were allowed to stand at room temperature
over a period of 3 days. Separately, Samples were subjected to forced
aging test. Thus, samples were also allowed to stand at a temperature of
50.degree. C. and a relative humidity of 80% over a period of 3 days.
Thereafter, each sample is sandwiched between the intensifying screens (1
or 2), exposed to X-ray through a penetrometer type B (product by Konica
Medical), and processed with SRX-503 automatic processor, which was
provided with a input member of a solid processing composition, according
to the replenishing rate and the processing time described above. A
sensitivity was defined as a reciprocal of X-ray exposure necessary for
giving a density of minimum density plus 1.0. The sensitivity was
expressed as a relative vale, based on the sensitivity of sample 1 being
100, when sandwiched with Screen-1.
Photographic material samples were exposed so as to give a density of 1.0
and subjected to running-processing. During running-processing, two tablet
(A) and two tablet (B) per 0.62 m.sup.2 of the photographic material were
supplied to the developing solution, with 76 ml of water. When one tablet
of each (A) and (B) were dissolver in water of 38 ml, its pH was 10.70. To
the fixing solution, two tablets of (C) and one tablet of (D) were added
with 74 ml of water. Addition of water was started at the same time of
that of the tablets and continued at a constant rate further for 10 min.
in proportion to a dissolving rate of the solid processing composition.
Evaluation of Covering Power:
Each sample was subjected to exposure giving the maximum density and
processed in a manner similar to the sensitometric evaluation. Processed
samples each were subjected to fluorescent X-ray analysis to determine the
silver amount (g/m.sup.2). Covering power was determined according to the
following equation:
Covering Power (CP)=(Maximum Density/Silver Amount).times.100.
Evaluation of Pressure Resistance
Under humidifying conditions at 50% R.H., one end of the photographic
material sample was fixed and bent along a stainless pipe with 8 mm
diameter at a bending rate of 360.degree./sec and with rotating
180.degree.. After processing, an increased fog density at bent portions
was measured.
Evaluation of Silver Image Color
Photographicmaterial samples, each with a size of 10 cmx 30 cm was exposed
with sandwiching between intensifying screens-1 and processed in a manner
similar to sensitometry evaluation. Precessed samples were visually
evaluated, based on the following criteria:
5: No yellowish color and neutrak black
4: Very slightly yellowish color
3: Yellowish color but acceptable level in practical use
2: Strongly yellowish color and problem in practical use
1: Markedly yellowish color and non-acceptable in practical use.
Results are shown in Tables 3 and 4.
TABLE 3
__________________________________________________________________________
Sam-
Emul-
Intensifying screen 1
ple
sion
Processing-1 Processing-2
Processing-3
No.
No. Fog
S CP PR SIC
Fog
S CP SIC
Fog
S CP SIC
Remark
__________________________________________________________________________
1 1 0.05
100
55 0.32
2 0.05
85 50 1 0.05
88 50 1 Comp.
2 2 0.05 100 55 0.35 2 0.05 85 50 1 0.05 88 50 1 Comp.
3 3 0.05 115 50 0.36 1 0.05 100 43 1 0.05 102 45 1 Comp.
4 4 0.06 120 56 0.35 1 0.05 105 52 1 0.06 106 55 1 Comp.
5 5 0.05 120 57 0.36 1 0.05 105 51 1 0.05 106 54 1 Comp.
6 6 0.04 125 59 0.35 3 0.04 106 51 2 0.05 109 54 1 Comp.
7 7 0.01 164 68 0.05 5 0.01 163 68 5 0.01 164 68 5 Inv.
8 8 0.01 165 69 0.04 5 0.01 164 69 5 0.01 165 69 5 Inv.
9 9 0.04 125 59 0.36 3 0.04 104 51 2 0.05 107 53 2 Comp.
10 10 0.01 166 70 0.03 5 0.01 164 69 5 0.01 165 69 5 Inv.
11 11 0.01 165 70 0.03 5 0.01 163 69 5 0.01 164 69 5 Inv.
12 12 0.01 162 69 0.03 5 0.01 160 69 5 0.01 164 70 5 Inv.
13 13 0.05 125 60 0.32 3 0.05 100 53 3 0.05 101 55 2 Comp.
14 14 0.04 125 62 0.35 3 0.04 100 55 3 0.05 101 55 2 Comp.
15 15 0.01 166 72 0.03 5 0.01 164 71 5 0.01 167 72 5 Inv.
16 16 0.01 166 71 0.02 5 0.01 164 71 5 0.01 167 72 5 Inv.
__________________________________________________________________________
TABLE 4
__________________________________________________________________________
Sam-
Emul-
Intensifying screen 2
ple
sion
Processing-1 Processing-2
Processing-3
No.
No. Fog
S CP PR SIC
Fog
S CP SIC
Fog
S CP SIC
Remark
__________________________________________________________________________
1 1 0.05
61 55 0.32
2 0.05
52 50 1 0.05
54 50 1 Comp.
2 2 0.05 61 55 0.35 2 0.05 52 50 1 0.05 54 50 1 Comp.
3 3 0.05 70 50 0.36 1 0.05 61 43 1 0.05 62 45 1 Comp.
4 4 0.06 73 56 0.35 1 0.05 64 52 1 0.06 65 55 1 Comp.
5 5 0.05 73 57 0.36 1 0.05 64 51 1 0.05 65 54 1 Comp.
6 6 0.04 76 59 0.35 3 0.04 65 51 2 0.05 66 54 1 Comp.
7 7 0.01 100 68 0.05 5 0.01 99 68 5 0.01 100 68 5 Inv.
8 8 0.01 101 69 0.04 5 0.01 100 69 5 0.01 101 69 5 Inv.
9 9 0.04 76 59 0.36 3 0.04 63 51 2 0.05 65 53 2 Comp.
10 10 0.01 101 70 0.03 5 0.01 100 69 5 0.01 101 69 5 Inv.
11 11 0.01 101 70 0.03 5 0.01 99 69 5 0.01 100 69 5 Inv.
12 12 0.01 99 69 0.03 5 0.01 98 69 5 0.01 100 70 5 Inv.
13 13 0.05 76 60 0.32 3 0.05 61 53 3 0.05 62 55 2 Comp.
14 14 0.04 76 62 0.35 3 0.04 61 55 3 0.05 62 55 2 Comp.
15 15 0.01 101 72 0.03 5 0.01 100 71 5 0.01 102 72 5 Inv.
16 16 0.01 101 71 0.02 5 0.01 100 71 5 0.01 102 72 5 Inv.
__________________________________________________________________________
As can be seen from Tables 3 and 4, inventive samples exhibited superior
results to comparative samples.
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